研究者詳細 - 趙　孟佑

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Experimental study on photodiode array sensor aided MEMS fine steering mirror control for laser communication platforms 査読有り国際誌

Ishola F., Cho M.

IEEE Access 9 100197 - 100207 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Line-of-sight laser communication application scenarios are numerous including land, mobile, maritime, airborne and space platforms for conventional and tactical utilization. However, beam pointing and stabilization are complicated in dynamic systems such as orbiting satellite to ground receiver, drones, aircrafts and metropolitan free-space optical links vulnerable to natural and artificial disturbances. Small Satellite platforms such as CubeSats are even more challenging due to their limited size and on-board resources. This paper presents an experimental study on a feedback photodiode array sensor assisted control of a one-axis micro-electromechanical (MEMS) fine steering mirror stabilizing a laser communication link on an optical bench in the laboratory. Disturbance profiles similar to vibrations on dynamic platforms are induced into the setup using an electrodynamic vibration machine to test the efficacy of the MEMS fine steering control mechanism. The Photodiode Array (PDA) sensor collocated with an Avalanche Photodiode at the receiving section provides sustained information about the transmitter's movements and beam displacements while the received optical signal strength is continuously monitored. The feedback signals are transmitted to the FSM controller via a radio link. We demonstrate the capacity to stabilize a laser beam transmission in the presence of external disturbances and platform movements using a PDA sensor assisted control.

DOI： 10.1109/ACCESS.2021.3096816

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Lessons learned and initial results from birds ground station network 査読有り国際誌

Jirawattanaphol A., Cho M.

Advances in the Astronautical Sciences 173 643 - 651 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Communication time between satellites in the LEO and ground stations are usually limited. Increasing communication data rate may not be an option as it may increase satellite cost and impose more requirements on power generation. Using ground station network for constellation of satellites increases the communication window between satellites and ground stations. BIRDS ground station network (GSN) was established in 2015 to support the missions of BIRDS-1 satellites constellation as part of an educational satellite program named BIRDS at Kyushu Institute of Technology (Kyutech). The GSN propagated into supporting the missions of BIRDS-2 and BIRDS-3 satellites and other small satellites operating on VHF/UHF. Currently, the BIRDS GSN has fifteen member countries with ground stations installed in each country across the world in South America, Africa and Asia connected by internet and managed by Kyutech. This paper presents challenges and lessons learned in establishing ground stations in participating countries such as the insufficiency of technical skills and knowledge to set up and operate the local ground station. The BIRDS GSN has been successful to increase the time resolutions and significantly reduced time to download images from BIRDS-3 satellites.

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On-Orbit Magnetometer Data Calibration Using Genetic Algorithm and Interchangeability of the Calibration Parameters 査読有り国際誌

Withanage D.C., Teramoto M., Cho M.

Applied Sciences (Switzerland) 13 ( 11 ) 2023年06月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Magnetometers are important sensors with applications in the attitude determination and control systems of satellites. CubeSats have certain limitations related to power, mass, and volume. Due to this, CubeSat magnetometers are not separated from other electrical circuits inside the satellite. Thus, it is important to calibrate the magnetometer, simulating operating conditions while the satellite is running before the launch. However, due to the limited facilities, not every CubeSat is able to calibrate its magnetometers properly on the ground. This study focuses on the calibration of on-orbit magnetometer data observed by BIRDS-3 CubeSats with a genetic algorithm. High oscillations in the total magnetic field were found in the on-orbit magnetic field data measured by magnetometers inside BIRDS-3 CubeSats. Nine unknowns, scaling factors, non-orthogonal angles, and offsets are identified with the genetic algorithm. This paper discusses the factors that affect the high oscillations in the measured total magnetic field data. For the calibration, we used magnetic field data similar to those of a model magnetic field, as the deviation is smaller. This paper presents the accuracy of determining unknowns using the genetic algorithm, as well as the interchangeability of the answers with additional orbit data from the same satellite. This method can be used in the future to calibrate magnetometers inside CubeSats before or after launch.

DOI： 10.3390/app13116742

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Integration of a UHF Fractal Antenna into a 1U CubeSat for Low-Earth Orbit Mission 査読有り

Raynell A. Inojosa, Celso B. Co, and Mengu Cho

International Conference on Advances in Communication Technology and Computer Engineering 2023年02月

Revision of ISO-19683 for constellation testing 査読有り

Mengu Cho

5th International Workshop on Lean Satellite 2023年01月

UNISEC-Global - Past, Present and Future 査読有り国際誌

Kawashima R., Ibrahim M.K., Steyn H., Nakasuka S., Aslan A.R., Cho M.

Proceedings of 10th International Conference on Recent Advances in Air and Space Technologies, RAST 2023 2023年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

University Space Engineering Consortium (UNISEC)-Global has contributed to promoting and supporting practical space projects at the university level worldwide. Initially., the university consortium activities started in Japan in 2002., and currently., it has 24 Local Chapters (LCs) and 63 Points Of Contact (POC) worldwide. UNISEC-Global aims to create a world where university students in all countries/regions can participate in practical space projects and provide educational programs such as CanSat/CubeSat Leader Training Program (CLTP), Mission Idea Contest (MIC) for nano/micro satellite utilization. Also, it provides a forum where people can exchange information, knowledge, and views by organizing in-person and virtual conferences/meetings. Recent changes in the space situation caused by mega-constellation missions have impacted university satellite projects. UNISEC-Global needs diverse experts' support, and restructuring the organization is essential to involve all stakeholders. Given the problematic space situations, future directions are discussed, and three proposals, creating working groups, empowering Local Chapters, and launching UNISEC constellation mission(s), are presented.

DOI： 10.1109/RAST57548.2023.10197659

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BIRDS Bus Open-Sourcing Activity 査読有り

布施哲人,趙孟佑

5TH INTERNATIONAL WORKSHOP ON LEAN SATELLITE 2023年01月

Design improvement of a thermoelectric device-based thermal vacuum chamber 査読有り

Mattei GIULIO, Joseph Ampadu OFOSU, Hirokazu MASUI, and Mengu CHO

5th International Workshop on Lean Satellite 2023年01月

Onboard Image Classification for Nanosatellites to Improve Data Downlink Efficiency 査読有り

Keenan Chatar, Kitamura Kentaro, Abhas Maskey and Mengu Cho

10th International Symposium on Applied Engineering and Sciences 2022年12月

Exploiting Fractal Geometry in the Design of a UHF Patch Antenna for Low-Earth Orbit Nanosatellite Applications 査読有り

Raynell A. Inojosa, Celso B. Co, and Mengu Cho

2022 Graduate Research Forum for Technology, Engineering, and Computing (Graf-TEC 2022) 2022年12月

On-orbit Electrical Power System Dataset of 1U CubeSat constellation 査読有り

Adolfo Javier Jara Cespesdes; Pooja Lepcha; Sangkyun Kim; Hirokazu Masui; Takashi Yamauchi; George Maeda; Mengu Cho

Data in Brief 2022年12月

Electrodynamic Analysis of a Geometry-Oriented Antenna for Low-Earth Orbit CubeSat 査読有り

Raynell A. Inojosa, Celso B. Co, and Mengu Cho,

2022 IEEE Transdisciplinary-Oriented Workshop for Emerging Researchers (TOWERS) 2022年11月

Surface Potential Measurement with Pockels Effect Under Electron Beam and Vacuum Ultraviolet 査読有り国際誌

Toyoda K., Kose S., Cho M.

Journal of Spacecraft and Rockets 59 ( 6 ) 2202 - 2205 2022年11月

Assessment of Intra-Urban Heat Island in a Densely Populated City Using Remote Sensing: A Case Study for Manila City 査読有り国際誌

Purio M.A., Yoshitake T., Cho M.

Remote Sensing 14 ( 21 ) 2022年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Changes in the environment occur in cities due to increased urbanization and population growth. Sustainable Development Goal (SDG) 11 is intrinsically linked to the environment, one facet of which is the need for universal access to secure, inclusive, and accessible green and public places. As urban heat islands (UHI) have the potential to negatively influence cities and their residents, existing resources and data must be used to identify and quantify these effects. To address this, we present the use of satellite-derived (2013–2022) and meteorological data (2014–2020) to assess intra-urban heat islands in Manila City, Philippines. The assessment includes (a) understanding the temporal variability of air temperature measurements and outdoor thermal comfort based on meteorological data, (b) comparative and correlative analysis between common Land-Use Land Cover indicators (Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI) and Normalized Difference Built-up Index (NDBI)) and Land Surface Temperature (LST), (c) spatial and temporal analysis of LST using spatial statistics techniques, and (d) generation of an intra-urban heat island (IUHI) map with a recommended class of action using a suitability analysis model. Finally, the areas that need intervention are compared to the affected population, and suggestions to enhance the thermal characteristics of the city and mitigate the effects of UHI are established.

DOI： 10.3390/rs14215573

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Design and environmental testing of imaging payload for a 6U CubeSat at low Earth orbit: KITSUNE mission. 査読有り

Muhammad Hasif Bin Azami, Necmi Cihan Örger, Victor Hugo Schulz, Takashi Oshiro, Jose Rodrigo Cordova Alarcon, Abhas Maskey, Kazuhiro Nakayama, Yoshiya Fukuda, Kaname Kojima, Takashi Yamauchi, Hirokazu Masui, Mengu Cho

Frontiers in Space Technologies 2022年11月

SmallSat NanoSat strategy at Kyushu Institute of Technology 査読有り

布施哲人,趙孟佑

International Conference on Aerospace Science and Technology 2022 2022年11月

Open-Sourcing of CubeSat Bus for Capacity Building aimed to Acquire Original Space Development Capability 査読有り

布施哲人,趙孟佑

JOINT 3RD IAA LATIN AMERICAN SYMPOSIUM ON SMALL SATELLITES AND 5TH IAA LATIN AMERICAN CUBESAT WORKSHOP 2022年11月

Revision Strategy of Lean Satellite Testing Standard ISO-19683 査読有り

Mengu Cho, Joseph Ofosu, Takashi Yamauchi, Hirokazu Masui

11th Nanosatellite Symposium 2022年10月

BIRDS-4 1U CubeSat Missions and On-Orbit Results 査読有り

Hari Ram Shrestha, BIRDS-4 Project Members, George Maeda, Sangkyun Kim1, Hirokazu Masui1, Takashi Yamauchi1, Mengu Cho

11th Nano-Satellite symposium 2022年10月

Development of an efficient Mono-frame CubeSat platform for fast and demanding missions 査読有り

Eyoas Ergetu AREDA*, Hirokazu MASUI, Mengu CHO

11th Nanosatellite Symposium 2022年10月

Mission Assurance Handbook for University-based Lean Satellites 査読有り

Mengu Cho, Yoshihiro Tsuruda, Masahiro Furumoto, Kikuko Miyata, Yukihito Kitazawa, Toshinori Kuwahara

73rd International Astronautical Congress 2022年09月

Lower Ultra-High Frequency Non-Deployable Omnidirectional Antenna for Nanosatellite Communication System 査読有り

Alam T., Sheikh M.M., Aldhaheri R.W., Singh M.S.J., Cho M., Islam M.T., Alharbi K.H., Islam M.S.

Nanomaterials 12 ( 18 ) 2022年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The concept of the nanosatellite comes into play in launching miniaturized versions of satellites or regarding payloads with minimizing cost and building time. The economic affordability of nanosatellites has been promoted with a view to launching various nanosatellite missions. The communication system is one of the most important aspects of a satellite. The antenna is a key element for establishing a communication link between the earth and the nanosatellite. The antenna and solar panel of the nanosatellite are two of the most vital components that profoundly impact antenna type and design. This paper proposes a non-deployable lower ultra-high frequency (UHF) antenna, strategically mounted on the satellite body, to address the constraints of deployment complexity and solar panel integration. The antenna was fabricated and performances measured with a 1U nanosatellite structure, which achieved resonance frequency at 401 MHz frequency bands with 0.672 dBi realized gain. The overall antenna size is 0.13λ × 0.13λ × 0.006λ. The major challenges addressed by the proposed antenna are to design a nanosatellite-compatible lower UHF antenna and to ensure solar irradiance into the solar panel to minimize input power scarcity.

DOI： 10.3390/nano12183143

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Scalable and Configurable Electrical Interface Board for Bus System Development of Different CubeSat Platforms 査読有り国際誌

Sejera M., Yamauchi T., Orger N.C., Otani Y., Cho M.

Applied Sciences (Switzerland) 12 ( 18 ) 2022年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

A flight-proven electrical bus system for the 1U CubeSat platform was designed in the BIRDS satellite program at the Kyushu Institute of Technology. The bus utilizes a backplane board as the mechanical and electrical interface between the subsystems and the payloads. The electrical routes on the backplane are configured by software using a complex programmable logic device (CPLD). It allows for reusability in multiple CubeSat projects while lowering costs and development time; as a result, resources can be directed toward developing the mission payloads. Lastly, it provides more time for integration and system-level verification, which are critical for a reliable and successful mission. The current trend of CubeSat launches is focused on 3U and 6U platforms due to their capability to accommodate multiple and complex payloads. Hence, a demonstration of the electrical bus system to adapt to larger platforms is necessary. This study demonstrates the configurable electrical interface board’s scalability in two cases: the capability to accommodate (1) multiple missions and (2) complex payload requirements. In the first case, a 3U-size configurable backplane prototype was designed to handle 13 mission payloads. Four CPLDs were used to manage the limited number of digital interfaces between the existing bus system and the mission payloads. The measured transmission delay was up to 20 ns, which is acceptable for simple serial communications such as UART and SPI. Furthermore, the measured energy consumption of the backplane per ISS orbit was only 28 mWh. Lastly, the designed backplane was proven to be highly reliable as no bit errors were detected throughout the functionality tests. In the second case, a configurable backplane was implemented in a 6U CubeSat with complex payload requirements compared to the 1U CubeSat platform. The CubeSat was deployed in ISS orbit, and the initial on-orbit results indicated that the designed backplane supported missions without issues.

DOI： 10.3390/app12188964

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Performance Evaluation of Machine Learning Methods for Anomaly Detection in CubeSat Solar Panels 査読有り国際誌

Cespedes A.J.J., Pangestu B.H.B., Hanazawa A., Cho M.

Applied Sciences (Switzerland) 12 ( 17 ) 2022年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

CubeSat requirements in terms of size, weight, and power restrict the possibility of having redundant systems. Consequently, telemetry data are the primary way to verify the status of the satellites in operation. The monitoring and interpretation of telemetry parameters relies on the operator’s experience. Therefore, telemetry data analysis is less reliable, considering the data’s complexity. This paper presents a Machine Learning (ML) approach to detecting anomalies in solar panel systems. The main challenge inherited from CubeSat is its capability to perform onboard inference of the ML model. Nowadays, several simple yet powerful ML algorithms for performing anomaly detection are available. This study investigates five ML algorithm candidates, considering classification score, execution time, model size, and power consumption in a constrained computational environment. The pre-processing stage introduces the windowed averaging technique besides standardization and principal component analysis. Furthermore, the paper features the background, bus system, and initial operational data of BIRDS-4, a constellation made of three 1U CubeSats released from the International Space Station in March 2021, with a ML model proposal for future satellite missions.

DOI： 10.3390/app12178634

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Development of Innovative CubeSat Platform for Mass Production 査読有り国際誌

Areda E.E., Cordova-Alarcon J.R., Masui H., Cho M.

Applied Sciences (Switzerland) 12 ( 18 ) 2022年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Featured Application: The presented innovative design concept significantly impacts the development of nanosatellites such as CubeSats, particularly for mass production missions that demand high efficiency and fast delivery. With the recent increase in CubeSats’ ability to undertake complex and advanced missions, they are being considered for missions such as constellations, which demand high development efficiency. From a satellite interface perspective, productivity can be maximized by implementing a flexible modular structural platform that promotes easy reconfigurability during the integration and testing phase. Thus, the structural design of a CubeSat plays a crucial role in facilitating the satellite integration process. In most cases, the mechanical interface implemented between the primary load-supporting structure and internal satellite subassemblies affects the speed and efficiency of satellite integration by adding or reducing complexity. Most CubeSat structural designs use stacking techniques to mount PCBs onto the primary structure using stacking rods/screws. As a result, the internal subsystems are interconnected. This conventional interface method is observed to increase the number of structural parts, while increasing complexity during integration. In this study, flexible 3U and 1U CubeSat platforms are developed, based on the slot concept. This innovative mounting design provides a simple method of mounting PCBs into the slots. The concept is evaluated and verified for its feasibility for mass production applications. Count and complexity analysis is carried to evaluate the proposed design against the conventional type of structural interface methods. The assessment reveals that this new concept demonstrates a significant improvement in the efficiency of the mass production process.

DOI： 10.3390/app12189087

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Assessing the Capacity and Coverage of Satellite IoT for Developing Countries Using a CubeSat 査読有り国際誌

Lepcha P., Malmadayalage T.D., Örger N.C., Purio M.A., Duran F., Kishimoto M., El-Megharbel H.A., Cho M.

Applied Sciences (Switzerland) 12 ( 17 ) 2022年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Many regions in developing countries do not have any access to communication networks even though the number of devices connected through the Internet of Things (IoT) is increasing significantly. A small satellite platform could provide global network coverage in low Earth orbit to these remote locations at a low cost. This paper describes the overall mission architecture and the implementation of remote IoT using a 1U volume in 6U CubeSat platform named KITSUNE. In KITSUNE, one of the missions is to leverage IoT for building a network of remote ground sensor terminals (GST) in 11 mostly developing countries. This paper evaluates the capacity and coverage of a satellite-based IoT network for providing remote data-collection services to these countries. The amount of data that could be collected from the GSTs and forwarded accurately to the users determines the actual capacity of the Store and Forward (S&F) mission. Therefore, there are several proposed parameters to estimate this capacity in this study. In addition, these parameters are retrieved from the simulations, ground test results, and on-orbit observations with the KITSUNE satellite. The proposed IoT system, which is composed of the GSTs and IoT subsystem onboard KITSUNE satellite, is determined to be capable of providing valuable information from remote locations. In addition, the collected data are achieved and analyzed to monitor sensory data specific to each country, and it could help to generate prediction profiles as well.

DOI： 10.3390/app12178623

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RESULTS OF BIRDS-4 SATELLITE ON-ORBIT POWER PERFORMANCE FOR ENHANCING 1U SATELLITE POWER SYSTEM RELIABILITY 査読有り

Hari Ram Shrestha, Izrael Zenar Casople Bautista, Adolfo Javier Jara Cespedes, BIRDS-4 team, Takashi Yamauchi, Mengu Cho

73rd International Astronautical Congress (IAC) 2022年09月

Open-Sourcing of CubeSat Bus for Capacity Building aimed to Acquire Original Space Development Capability 査読有り

布施哲人,趙孟佑

29th Workshop on Space Technology for Socio-Economic Benefits 2022年09月

Reconfigurable Software Defined Radio (SDR) Transceiver with Selective Frequency Algorithm for Atmospheric Radio Sensing Measurements on Small Satellites 査読有り

Ramson M. Nyamukondiwaa*, Mengu Cho, Makiko Kishimoto

73rd International Astronautical Congress (IAC) 2022年09月

OPERA: Onboard Processing Orbit Determination by One-Way Ranging for Lunar Exploration Mission 査読有り

Makiko Kishimoto, Sangkyun Kim, Shota Kubo, Kenta Sawa, Mengu Cho

73rd International Astronautical Congress (IAC) 2022年09月

Establishing a network of ground sensor terminals (GSTs) for satellite-based global store and forward data collection mission in developing nations 査読有り

Pooja Lepcha, Tharindu Dayarathna, Necmi C. Orger, Nik A.A. Rahmat, Federico Gaona, Ever Quiñonez, Sagar Koirala, Sirash Sayanju, Yu-Sheng Liu, Barsbold Bayansan, Turtogtokh Tumenjargal, Tuguldur Ulambayar, Mengu Cho

73rd International Astronautical Congress 2022年09月

Program management for sustainable university CubeSat programs based on the experience of five generations of CubeSat projects, BIRDS program 査読有り

Mengu Cho, Mariko Teramoto, Takashi Yamauchi, George Maeda, Sangkyun Kim, Hirokazu Masui

Small Satellite Conference 2022年08月

Open-sourcing 1U CubeSat platform for Education and Capacity Building 査読有り

Mengu Cho, George Maeda, Sangkyun Kim, Takashi Yamauchi, Hirokazu Masui, Kentaro Kitamura, Juan José Rojas Hernández

CubeSat Developers Workshop 2022年04月

Performance evaluation of MgF2 coated Electron Emitting Film for preventing spacecraft charging under vacuum ultraviolet environment 査読有り

濱田大毅，趙孟佑，豊田和弘

The 16th Spacecraft Charging and Technology Conference (SCTC) 2022年04月

Earth Observation Mission of a 6U CubeSat with a 5-Meter Resolution for Wildfire Image Classification Using Convolution Neural Network Approach 査読有り国際誌

Azami M.H.B., Orger N.C., Schulz V.H., Oshiro T., Cho M.

Remote Sensing 14 ( 8 ) 2022年04月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The KITSUNE satellite is a 6-unit CubeSat platform with the main mission of 5-m-class Earth observation in low Earth orbit (LEO), and the payload is developed with a 31.4 MP commercial off-the-shelf sensor, customized optics, and a camera controller board. Even though the payload is designed for Earth observation and to capture man-made patterns on the ground as the main mission, a secondary mission is planned for the classification of wildfire images by the convolution neural network (CNN) approach. Therefore, KITSUNE will be the first CubeSat to employ CNN to classify wildfire images in LEO. In this study, a deep-learning approach is utilized onboard the satellite in order to reduce the downlink data by pre-processing instead of the traditional method of performing the image processing at the ground station. The pre-trained CNN models generated in Colab are saved in RPi CM3+, in which, an uplink command will execute the image classification algorithm and append the results on the captured image data. The on-ground testing indicated that it could achieve an overall accuracy of 98% and an F1 score of a 97% success rate in classifying the wildfire events running on the satellite system using the MiniVGGNet network. Meanwhile, the LeNet and ShallowNet models were also compared and implemented on the CubeSat with 95% and 92% F1 scores, respectively. Overall, this study demonstrated the capability of small satellites to perform CNN onboard in orbit. Finally, the KITSUNE satellite is deployed from ISS on March 2022.

DOI： 10.3390/rs14081874

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Transparent S-band patch array antenna for a lunar mission CubeSat 査読有り

Daisuke Nakayama, Mengu Cho,

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-06, Beppu, Japan, Feb-Mar. 2022 (online) 2022年03月

Attitude and Orbit Control system for a 6U CubeSat mission in low altitude lunar orbit using low-thrust propulsion system 査読有り

Jose Rodrigo Cordova Alarcon, Matteo Laterza, Necmi Cihan Orger, Tze King Lam, Kai Sheng Khoo, George-Christian Potrivitu, Jian Wei Mark Lim, Sangkyun Kim, Mengu Cho,

33rd International Symposium on Space Technology and Science (ISTS) 2022年02月

Urban Growth Impact Assessment for Urban-Heat Island and Outdoor Thermal Comfort using data fusion technique for Manila City, Philippines 査読有り

Mark Angelo Purio, Tetsunobu Yoshitake, Mengu Cho,

33rd International Symposium on Space Technology and Science (ISTS), 2022-n-13, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Thermal Design of 6U Satellite KITSUNE Equipped with a High-Resolution Camera 査読有り

Takashi Oshiro, Mengu Cho, Hirokazu Masui, Takashi Yamauchi, Muhammad Hasif Bin Azami, Necmi Cihan Orger, Kazuhiro Nakayama,

33rd International Symposium on Space Technology and Science (ISTS), 2022-i-07, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Performance evaluation of thermoelectric device for thermal vacuum testing of nanosatellites 査読有り

J.A. Ofosu, H. Masui, M. Cho,

33rd International Symposium on Space Technology and Science (ISTS), 2022-i-05, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

To Develop a Standardized Back Plane Board Based on the BIRDS Satellites 査読有り

Yukihisa Otani, Mengu Cho, Sangkyun Kim, Takashi Yamauchi, Marloun Pelayo Sejera

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-54, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Scalability of Kyutech Standardized Electrical Power System for Lean satellites 査読有り

Pooja Lepcha, Tharindu Dayarathna, Victor Hugo Schulz, Necmi Cihan Orger, Jose Rodrigo Cordova-Alarcon, Hari Ram Shrestha, Sangkyun Kim, Takashi Yamauchi, Hirokazu Masui, Mengu Cho,

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-53, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Adaptability and Scalability of Configurable Interface Board for Different CubeSat Platforms and Missions 査読有り

Marloun Sejera, Takahashi Yamauchi, Yukihisa Otani, Mengu Cho,

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-52, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Development of Flexible 3U CubeSat Structural Platform for Mass Production Applications 査読有り

Eyoas Ergetu Areda, Takashi Yamauchi, Cordova Rodrigo, Masui Hirokazu, Mengu Cho,

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-51, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Comparison Study of Machine Learning Methods for CubeSat Anomaly Detection 査読有り

Adolfo Javier Jara Cespedes, Bramandika Holy Bagas Pangestu, Akitoshi Hanazawa, Mengu Cho

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-44, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Attitude determination and control system for the 6U CubeSat KITSUNE 査読有り

Jose Rodrigo Cordova Alarcon, Adolfo Javier Jara-Cespedes, Dulani Chamika Withanage, Victor Hugo Schultz, Necmi Cihan Orger, Sangkyun Kim, Mengu Cho

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-40, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Development of KITSUNE: A 6U CubeSat for 5-m Class Imaging, C-band Radio Service, Ionospheric Research and IoT 査読有り

N.C. Orger, J.R. Cordova-Alarcon, V.H. Schulz, T. Dayarathna, T. Yamauchi, H. Masui, O.J. Ampadu, S. Kim, M. Teramoto, P. Lepcha, D. Nakayama, M.P. Sejera, M.H.B. Azami, M. Kishimoto, C.C. Lap, K.H.L. Holden, H. Harada, Y. Fukuda, K. Kojima , M. Cho

, 33rd International Symposium on Space Technology and Science (ISTS), 2022-f-21, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Development of the Whisker Verification Experiment Satellite "FUTABA" 査読有り

Akihiro Oboshi, Mengu Cho, Hirokazu Masui,

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-14, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Development of a Double Langmuir Probe that can be Mounted on a Nano-Satellite 査読有り

Kohei Kamitani, Hirokazu Masui, Mengu Cho,

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-10, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Development of 2U satellite "MITSUBA" for orbit demonstration of commercial components 査読有り

H. Masui, I. Kato, MITSUBA project, M. Cho,

33rd International Symposium on Space Technology and Science (ISTS), 2022-f-09, Beppu, Japan, Feb-Mar. 2022 (online) 2022年02月

Study of Cubesat Attitude Stabilization Using Low Power Magnetic Torquer 査読有り

Dulani Chamika Withanage, Mengu Cho, Mariko Teramoto, Sangkyun Kim, Hirokazu Masui, Abhas Maskey, Yuta Kakimoto, Yuji Sasaki, Makiko Kishimoto, Tharindu Lakmal Dayarathna Malmadayalage, Hari Ram Shrestha, Pooja Lepcha,

33rd International Symposium on Space Technology and Science (ISTS) 2022年02月

Time Difference Detection of Atomic Clock-Based Reference Signal from a CubeSat in Orbit 査読有り国際誌

Rahmatillah R., Ninagawa R., Aheieva K., Adebolu I.O., Kakimoto Y., Masui H., Jirawattanaphol A., Yamauchi T., Kim S., Cho M., Hoda Awny E., Kishimoto M., Teramoto M., Lap Chow C., Holden Li K.H.

International Review of Aerospace Engineering 15 ( 1 ) 36 - 49 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Satellite signal delays and errors depend on the amount of ionosphere Total Electron Content (TEC) in the signal path. The measurement of TEC has been mostly done using Global Navigation Satellite System (GNSS) signals. Signals from a satellite orbiting in lower altitude with lower frequencies than GNSS may provide more precise measurement of Total Electron Content (TEC). Space Precision Atomic Clock Timing Utility Mission (SPATIUM) is a program to do three-dimensional ionosphere mapping by a satellite constellation in Low Earth Orbit (LEO) measuring TEC with Ultra High Frequency (UHF) radio signals. The first technology demonstration satellite called SPATIUM-I, a 2U CubeSat, was deployed from the International Space Station in October 2018. The satellite emits a 467-MHz reference signal generated by a chip scale atomic clock. The signal is Spread Spectrum (SS)-modulated with 250 chips in 4 ms. This paper explains the methodologies and their results of detecting the signal time delay on the ground using a Software-Defined Radio (SDR). To improve the precision, a Global Positioning System (GPS) clock was used to put a time stamp on the satellite signal every 1 s. The time difference of two consecutive signals is the key method for deriving the TEC difference between two signal paths.

DOI： 10.15866/irease.v15i1.21136

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85128355572&origin=inward

Perovskite Solar Cells in Space: Evaluation of Perovskite Solar Cell Hole Transport Material in Space Environment 査読有り

BAUTISTA Izrael Zenar C., YANG Shuzhang, KUYYAKANONT Aekjira, IWATA Minoru, MA Tingli, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ( 一般社団法人日本航空宇宙学会 ) 65 ( 2 ) 95 - 107 2022年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Majority of spacecrafts rely on solar power as the main source of energy. The search for a lightweight and cost-efficient energy source with high power conversion efficiency (PCE) led to the development of organic-inorganic metal halide Perovskite solar cells (PSCs). In this paper, the performance of PSCs with different hole-transport material (HTM) prepared for in-orbit demonstration mission onboard CubeSats are compared under simulated space environment such as thermal cycling stress, high-vacuum, UV radiation and vibration. Results show that even though organic and inorganic HTM display superior initial PCE, Carbon HTM PSCs trumps them in terms of stability and is more practical for use in space. The paper also discusses the satellite mission and developed hardware for the first demonstration of Perovskite solar cells on-board a satellite to gather in-orbit information on the performance of Perovskite solar cells in low-earth orbit and how the ground test results would be verified.

DOI： 10.2322/tjsass.65.95

その他リンク： https://kyutech.repo.nii.ac.jp/records/7659

Development of CubeSat Magnetic Torquer Testing System in a Vacuum Environment 査読有り国際誌

Hisatsugu H., Cordova-Alarcon J.R., Kim S., Teramoto M., Cho M.

International Review of Aerospace Engineering 15 ( 1 ) 50 - 61 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

This paper discusses the development and instrumentation of an integrated facility based on an air-bearing table to test small ADCS actuators such as electric propulsion devices, reaction wheels, and magnetic torquers for CubeSats. It includes an automatic balancing system that corrects the center of mass of the testing platform and a Helmholtz cage for the simulation of the in-orbit geomagnetic environment inside the vacuum environment. Through experimental tests, it was observed that the attitude disturbances due to the aerodynamic drag and the viscous rotational friction in atmospheric conditions (~5×10-6 Nm) can be significantly decreased when the testing platform is placed inside a vacuum environment (~5×10-7 Nm). It was also observed that the vacuum condition facilitates the verification test of attitude control maneuvers using small magnetic torquers for CubeSats whose control torque is smaller than the attitude disturbance torque in atmospheric conditions. A demonstration test was performed to verify the attitude stabilization control by the magnetic torquers in vacuum conditions under a simulated geomagnetic field as in the International Space Station orbit using this integrated testing facility.

DOI： 10.15866/irease.v15i1.21180

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Difference in threshold voltage of arc inception between electron beam and ultraviolet environment: surface potential measurement with Pockels effect 査読有り

Kazuhiro Toyoda, Sayaka Kose, Mengu Cho,

AIAA SCITECH 2022 Forum 2022年01月

Scalability of Kyutech Standard Configurable Interface Board for Lean Satellites 査読有り

Marloun Sejera, Takahashi Yamauchi, Yukihisa Otani, Mengu Cho,

4th International Workshop on Lean Satellites, Jan. 2022 2022年01月

Utilization of Lean Satellites for Leveraging Internet of Things (IoT) using Low Power Ground Sensor Terminals (GSTs) 査読有り

Pooja Lepcha, Tharindu Dayarathna, Fatima Duran, Necmi Cihan Orger, Victor Schulz, Mark Angelo Purio, Fahd Moumi, Yoji Hirakata, Mengu Cho

4th International Workshop on Lean Satellites 2022年01月

Total Ionization Dose Measurement onboard a 1U CubeSat in Low Earth Orbit 査読有り国際誌

Oboshi A., Murase T., Masui H., Wei S., Chang J., Cho M.

Proceedings - IEEE International Symposium on Circuits and Systems 2022-May 1028 - 1032 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The TMCR (Total Ionizing Dose Measurement of COTS and Onboard Rad-Hard Components Mission) mission onboard BIRDS-4, a 1U CubeSat, is attempting to measure changes in the electrical properties of semiconductors due to total ionizing dose effects. The mission has two objectives. The mission has two objectives: the first is to verify the accuracy of the TID tests performed on the ground. The second is to validate a system to measure radiation dose from the change in drain current of commercially available MOSFET devices. Based on the measurement of 237 days in LEO of 51degree inclination and 400km altitude, no significant changes in drain current have yet been observed, indicating a deviation from the results of the ground tests.

DOI： 10.1109/ISCAS48785.2022.9937444

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Structural Failure Detection in Vibration Testing Using Machine Learning and Deep Learning 査読有り国際誌

Mukungunugwa V., Cho M., Hirokazu M.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Early satellite structural failure detection is of great importance in the development of satellites, especially during vibration testing. Satellite vibration testing is one of the most reliable tests in satellite development to verify the workmanship, structure design, and making fracture control plan. Currently, vibration testing involves a series of modal surveys, random vibration, sine-burst, etc. This is done for each axis, which is time-consuming, tedious, and slow in detecting failure. This causes major damage to the satellite, resulting in huge costs and project time delays, especially when building constellations. The fast achievement of constellation development is heavily impeded by the long testing time for vibration and huge data analysis. The need for a minimized vibration testing time and quick methods of determining failure from the acquired sensor data can greatly impact the satellite development process. Data science has created many gateways to solve engineering problems for automated systems using machine learning and deep learning. This paper outlines how to detect a structural failure through the examination of vibration data using machine learning and deep learning techniques. The research includes 3-axis normal and abnormal vibration testing to collect data using orthogonally mounted accelerometers on the Horyu satellite structure thermal model.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85167561660&origin=inward

RESULTS OF BIRDS-4 SATELLITE ON-ORBIT POWER PERFORMANCE FOR ENHANCING 1U SATELLITE POWER SYSTEM RELIABILITY 査読有り国際誌

Shrestha H.R., Bautista I.Z.C., Cespedes A.J.J., Yamauchi T., Cho M.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

As part of the BIRDS satellite program, the BIRDS-4 satellites were launched on February 21, 2021. The prime objective of Electrical Power System (EPS) in a CubeSat is to provide continuous power to all subsystems and payloads during the satellite's lifetime. While the satellites performed satisfactorily on-orbit, several points of failure in the EPS were noted based on the on-orbit operation of BIRDS-4 satellites despite extensive testing on the ground. This study aims to identify the issues of the power system failure and reasons that caused these failures in orbit. One of the major mistakes that was observed in these constellations were the workmanship error in the assembly of the solar cells that led to failure of one or more sides of solar panels on-orbit. This caused imbalance in the power budget. In this study, the authors analysed the housekeeping data of BIRDS-4 satellites. This paper also summarizes the lessons learnt based on the operation of the satellites on-orbit and recommendations on the testing procedure for EPS that could be resourceful for other lean satellite developers.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85167618304&origin=inward

RECONFIGURABLE SOFTWARE DEFINED RADIO (SDR) TRANSCEIVER WITH SELECTIVE FREQUENCY ALGORITHM FOR ATMOSPHERIC RADIO SENSING MEASUREMENTS ON SMALL SATELLITES 査読有り国際誌

Nyamukondiwa R.M., Cho M., Kishimoto M.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The atmospheric measurements of water vapor and ionosphere electron density are critical for global climate modeling and scientific research. Incorrect predictions of atmospheric conditions can lead to disruptive and hazardous weather patterns such as storms, hurricanes and tornadoes, which endanger infrastructure, humans and other living species. The possibility of taking atmospheric measurements using radio signals is being considered for small satellites. Radio wave propagation through the atmosphere is greatly influenced by total water vapor content (TWVC) and ionospheric total electron content (TEC). Multiple spread spectrum (SS) ranging signal frequencies are send from a network of ground stations to a constellation of satellites or between satellite to satellite in intersatellite link network (ISL) and based on time delay measured by chip scale atomic clock (CSAC), the atmospheric contents are deduced. The TWVC is independent of the frequency and TEC is dependent of the frequency, therefore by reconfiguring frequencies using software defined radio (SDR), water vapor can be distinguished from total electron content. A reconfigurable frequency selection algorithm was implemented on the Raspberry Pi-4 using open-source GNU radio software. Test results demonstrated the possibility to reconfigure SDR frequencies and this can be used for future atmospheric measurements and other radio sensing applications.

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OPERA: Onboard Processing Orbit Determination by One-Way Ranging for Lunar Exploration Mission 査読有り国際誌

Kishimoto M., Kim S., Kubo S., Sawa K., Cho M.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

This paper presents Onboard Processing of Earth-origin one-way RAdio ranging signal (OPERA) system overview and current development work status. Spacecraft need their own navigation system beyond Low Earth Orbit (LEO). The conventional navigation system for deep space exploration is two-way range and Doppler. A large parabolic antenna whose diameter is typically 50m is required at the ground station side to achieve this communication. To promote space exploration by universities without relying on the large parabolic antenna belonging mostly to space agencies, OPERA system uses multiple small parabolic antennas of several meters that can be installed at universities. OPERA system performs one-way ranging where RF ranging signals are sent from multiple ground stations to circumvent the need to transmit high power signals (hundreds of watts) from the spacecraft. RF range and range rate measurements are processed onboard and derive own position. The development of the OPERA system started at Laboratory of Lean Satellite Enterprises and In-Orbit Experiments (LaSEINE) of Kyushu Institute of Technology in 2021. OPERA is aiming for an orbit determination accuracy of 5km for the future lunar exploration missions. OPERA system will be demonstrated in LEO before operation in the lunar environment. A 3U CubeSat installed with the OPERA system will be launched to LEO in 2024.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85167608054&origin=inward

One Year On-Orbit Results of Improved Bus, LoRa Demonstration and Novel Backplane Mission of a 1U CubeSat Constellation 査読有り国際誌

Maskey A., Lepcha P., Shrestha H.R., Chamika W.D., Malmadayalage T.L.D., Kishimoto M., Kakimoto Y., Sasaki Y., Tumenjargal T., Maeda G., Kim S., Masui H., Yamauchi T., Cho M.

Transactions of the Japan Society for Aeronautical and Space Sciences ( 一般社団法人日本航空宇宙学会 ) 65 ( 5 ) 213 - 220 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The BIRDS series from Kyushu Institute of Technology has deployed 1U CubeSat constellations from International Space Station since 2017. BIRDS-3 was deployed in June 2019. Lessons learnt from BIRDS-1 and BIRDS-2 have been used to improve the bus system of BIRDS-3. Improvements have been made in On-Board Computer, Electrical Power and Communication systems. BIRDS-3 has implemented novel Backplane Mission which uses SoftCIB; an in-house designed software defined backplane interface board. The mission has the potential to standardize interface and cut down on development time. BIRDS-3 project has placed a LoRa module to check its performance in space. The module has the potential for future low-cost, low-powered Store and Forward mission and CubeSat communication system. This paper provides detailed information on the improved BIRDS bus system, LoRa Demonstration and Backplane Mission designs, and on-orbit results since its deployment in June 2019. The results presented are based on cumulative operation time of three years for three satellites operating each for a year. The satellites are functional and will remain in orbit until summer of 2021.

DOI： 10.2322/tjsass.65.213

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85138641002&origin=inward

Mission Assurance Handbook for University-based Lean Satellites 査読有り国際誌

Cho M., Tsuruda Y., Furumoto M., Miyata K., Kitazawa Y., Kuwahara T.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

A lean satellite is a satellite that utilizes non-traditional, risk-taking development and management approaches - with the aim to provide the value to the customer and/or stakeholders by realizing the satellite mission at low-cost and in short time. It is another name to express the nature of pico/nano/micro/small satellites. It is well known that the mission success rate of university-based lean satellites is much lower than those of traditional satellites or non-university-based lean satellites. In 2020, UNISEC (UNIversity Space Engineering Consortium) of Japan organized a series of online meetings to exchange the lessons learned from university satellite projects. Further analysis of the failure cases to extract their root causes led to making a handbook for mission assurance. The handbook gives summary of points to be kept in mind by faculty members and students to improve the mission success rate. The handbook is organized in the order of project life-cycle, i.e. from the mission definition to the operation with three additional chapters on project management, post-operation and sustainability of university satellite program. Although the handbook is based on the lessons learned of Japanese universities, many of those also apply to other countries and new space companies.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85167589338&origin=inward

Establishing a network of ground sensor terminals (GSTs) for satellite based global store and forward data collection mission in developing nations 査読有り国際誌

Lepcha P., Dayarathna T., Orger N.C., Rahmat N.A.A., Gaona F., Quiñonez E., Koirala S., Sayanju S., Liu Y.S., Bayansan B., Tumenjargal T., Ulambayar T., Cho M.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Kyushu Institute of Technology (Kyutech), Japan initiated and formed a network of ground sensor terminals (GSTs) with participants from 11 different agencies/institutions predominantly in developing countries for a CubeSat based store and forward (S&F) data collection mission. Most of the participating countries have no or significantly limited access to space technologies with inadequate space programs. Involvement of these countries in this collaborative network has enabled the participating countries with access to space development and utilization without having to launch satellites using their own resources. The basic design for the GST was envisioned at Kyutech, each of these countries have customized the design based on material substitutes available locally, optimizing the design for that country. The participants from each country are building their customized GSTs with applications that are most relevant in solving issues that arise locally. A S&F receiver payload was developed for a 6-unit CubeSat called KITSUNE at Kyutech. This paper states the challenges faced in these countries and the basis on which the sensors have been selected for the GST to solve these issues. Additionally, the paper describes the efforts undertaken by participants to build GST using local component substitutes while learning about the complexities and limitations of ground to satellite communications. The research aims to promote large scale space utilization and human capacity development in developing countries despite having constrained space programs. The country specific dataset collected by the satellite will be archived and analysed for generating prediction profiles and monitoring variables as a basis to address local data collection problems faced in the respective countries.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85167594365&origin=inward

Difference in threshold voltage of arc inception between electron beam and ultraviolet environment: surface potential measurement with Pockels effect 査読有り国際誌

Toyoda K., Kose S., Cho M.

AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The surface potential of insulator material was measured with Pockels effect in this paper. The threshold measurement showed the difference value between vacuum ultra violet and electron beam as charging method. To understand this result, the precise surface potential method is needed. The difference in surface potential distribution was acquired with optical surface potential measurement with Pockels effect.

DOI： 10.2514/6.2022-1989

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85123569845&origin=inward

Critical Plasma Environment for Space Debris Capturing Operation in Auroral Oval 査読有り国際誌

Okumura T., Teramoto M., Masui H., Cho M.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Aerospace Exploration Agency researches the technology for active space debris removal. The anti-charging measure at the moment of capture operation is one of research topics. In order to consider effective countermeasure, we need to know how much potential difference can be possible. As is well known, the charged particles that cause satellite charging depends on the type of orbit. We investigate the potential difference in the polar orbit, which is known as congested orbit populated by many space debris. Through this investigation, we expect to clarify the relationship between plasma environment and potential difference at capture operation. We utilize the past observation results by the DMSP satellites for the plasma environment conditions. We change the ionospheric plasma density from the order of 108/m3 to 1010/m3, and the current density of auroral electron from 1×10-4A/m to 1×10-6A/m. The other environmental parameters are shown in the presentation. We use Multi-Utility Spacecraft Charging Analysis Tool, MUSCAT to obtain the potential difference between the debris and the satellite. MUSCAT is a 3D charging simulation tool. We make the grid models of the satellite and the upper stage of H-II A rocket which is assumed as the removal target in the analysis domain. Whether the potential difference was safe or not was determined based on the Japanese spacecraft charging design guideline. The simulation result shows that if the plasma density is of the order of 1010/m3, the potential difference is low enough to ignore the risk of discharge. If the plasma density is lower than 1010/m3, the auroral electron current density is the dominant parameter for the potential difference. Since the risk of discharge depends on the plasma density, a device to measure the plasma density is necessary for a debris removal satellite.

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CoFFI: an image classification GUI for forest fire imagery applying convolution neural networks 査読有り国際誌

Azami M.H.b., Orger N.C., Schulz V.H., Cho M.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In the past decades, deep learning (DL) has been a powerful tool for image recognition. Any image acquired by a camera sensor or a satellite camera payload can now be rapidly classified using DL. At present, satellite imagery is being used to observe the weather and map natural disasters which occur globally, such as forest fires. On the other hand, high-resolution forest fire images from defined datasets are found to be difficult to obtain and be trained in DL models. In this study, a new forest fire dataset was collected from PlanetScope, Sentinel-2, and Landsat-8 and was pre-trained using convolution neural networks (CNN) models to create a GUI called CoFFI: a Classification of Forest Fire Imagery GUI in order to post-processing the image downlink from satellites. Four labels (cloud, land, sea, and wildfire) were trained using the existing networks and analyzed for accuracy and computational time. The training results showed the highest accuracy of 99%, with a 97% F1-score of wildfire labels utilizing the ResNet architecture. Other models were further evaluated and compared to show the effectiveness of the dataset created. Furthermore, these networks were also included in the CoFFI GUI as options to predict new images downloaded from satellites. The GUI was partially tested and verified for images acquired from KITSUNE 6U CubeSat, which captured non-forest fire images. Ultimately, this computer program would be valuable for other satellite projects by filtering first the enormous image data downlink to the ground station before providing it to the respective authority.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85167578906&origin=inward

BIRDS-4 Satellites Constellation: APRS Mission Preliminary Results for Remote Detection of Triatomines in the Paraguayan Chaco 査読有り国際誌

Cespedes A.J.J., Sejera M., Ferrer E.J., Gaona F., Cho M.

Proceedings of the International Astronautical Congress, IAC 2022-September 2022年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Until March 2021, Paraguay was the only South American country that did not have a satellite in space. The transition from its non-space faring nation status began in 2018 after joining the Joint Global Multi National Birds or BIRDS program, a multinational small satellite project led by Kyushu Institute of Technology (Kyutech) in Japan. The BIRDS program gives non-space faring nations the opportunity to design, integrate, build, test, launch, and operate their country's first satellite. The fourth edition of the BIRDS program (BIRDS-4) is developed by Kyutech jointly with the Paraguay Space Agency (AEP) and the University of the Philippines Diliman (UPD). It consists of three CubeSats, GuaraniSat-1 (Paraguay's first satellite), Maya-2 (Philippines), and Tsuru (Japan). All three satellites have the same design and among nine missions, one of them aims to collect data from ground sensor terminals (GST) and transmit it to a database storage server via satellite link. The GST comprises traps to detect the presence of arthropod insects in a remote indigenous village of the Paraguayan Chaco, where the insects that spread Chagas disease are persistent to infest the area. This paper describes the satellite mission design considering the space segment and ground segment, operation concept, initial operational results, lessons learned and the background of Paraguay's participation in the BIRDS-4 project. This paper also investigates technical challenges through experiments on appropriate data format and multiple access schemes while complying with limited operational time and power constraints using the APRS protocol, such that if proven successful, will be used for future satellite missions to gather data in remote areas.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85167592236&origin=inward

Metamaterial array based meander line planar antenna for cube satellite communication 査読有り

Alam T., Almutairi A.F., Samsuzzaman M., Cho M., Islam M.T.

Scientific Reports 11 ( 1 ) 2021年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

This research article presents a design and performance analysis of a metamaterial inspired ultra-high frequency (UHF) compact planar patch antenna for the CubeSat communication system that could be smoothly integrated with commercially available 2U Cube Satellite structure and onboard subsystem. The proposed antenna consists of two layers, one is two different width meander line antenna patch with partial ground plane and another layer is 3 × 2 near-zero-indexed metamaterial (NZIM) metamaterial array structure with ground plane. The NZIM array layer has been utilized to minimize the coupling effect with Cube Satellite structure and improve the frequency stability with enhanced antenna gain and efficiency. The fabricated antenna can operate within the lower UHF frequency band of 443.5–455 MHz. with an average peak gain of 2.5 dB. The designed antenna impedance stability characteristic has been explored after integration with the 2U Cube Satellite body layout. Besides, the antenna communication performance has been verified using 2U Cube Satellite free space path loss investigation. Small antenna volume with trade-off between the antenna size and performance are the key advantages of the proposed design, as the antenna occupies only 80 × 40 × 3.35 mm3 space of the 2U Cube Satellite body structure and the geometrical parameters can be designed to provide the best performance between 449 and 468.5 MHz.

DOI： 10.1038/s41598-021-93537-6

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85109762459&origin=inward

BIRDS-NEST Phone Application 査読有り

Fahd Moumni, Keenan Chatar, Sayaka Kose, Noruji Muto, Abhas Maskey, Sangkyun Kim,

72nd International Astronautical Congress (IAC) 2021年10月

On-Orbit Observation of Total Electron Content in the Ionosphere by UHF Ranging Signal from the Ground 査読有り

Makiko Kishimoto, Necmi Cihan Orger, Hoda Awny Elmegharbel, Tharindu Dayarathna, Pooja Lepcha, Takashi Yamauchi, Sangkyun Kim, Mariko Teramoto, Hirokazu Masui, Chee Lap Chow, Man Siu Tse, King Ho Li Holden,

72nd International Astronautical Congress (IAC), 2021年10月

Feasibility Study of Space Weather Observation by CubeSat in LEO 査読有り

北村健太郎, 趙孟佑, 吉川顕正, 魚住禎司, 阿部修司, 寺本万里子, 藤本晶子

第150回地球電磁気・地球惑星圏学会（SGEPSS）総会および講演会 2021年10月

Trajectory optimization for the Horyu-VI international lunar mission 査読有り国際誌

De Grossi F., Marzioli P., Cho M., Santoni F., Circi C.

Astrodynamics 5 ( 3 ) 263 - 278 2021年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The Horyu-VI nano-satellite is an international lunar mission with the purpose of studying the lunar horizon glow (LHG)—a still unclear phenomenon caused by electrostatically charged lunar dust particles. This study analyzes the mission trajectory with the hypothesis that it is launched as a secondary payload of the NASA ARTEMIS-II mission. In particular, the effect of the solar gravity gradient is studied; in fact, depending on the starting relative position of the Moon, the Earth, and the Sun, the solar gradient acts differently on the trajectory—changing it significantly. Therefore, the transfer and lunar capture problem is solved in several cases with the initial Sun–Earth–Moon angle as the key parameter. Furthermore, the inclination with respect to the Moon at capture is constrained to be equatorial. Finally, the problem of stabilization and circularization of the lunar orbit is addressed in a specific case, providing an estimate of the total propellant cost to reach the final orbit around the Moon. [Figure not available: see fulltext.]

DOI： 10.1007/s42064-021-0105-1

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85113751444&origin=inward

Experimental Investigation on Particle Size and Launch Angle Distribution of Lofted Dust Particles by Electrostatic Forces 査読有り国際誌

Necmi Cihan Orger, Kazuhiro Toyoda, Mengu Cho

Advances in Space Research ( ELSEVIER ) 68 ( 3 ) 1568 - 1581 2021年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Electrostatic dust transportation is one of the fundamental sources for dust activity on airless planetary bodies. Even though a series of laboratory experiments have been performed to improve our understanding of the physics behind the electrostatic dust mobilization, there are several factors to investigate such as the launch angles, the lofted particle sizes, the traveling distance of the lofted grains, the initial acceleration to the launching velocities and so on. In this experimental study, an electron beam is used with 450 eV energy to produce secondary electrons to initiate lofting of the silica microspheres in the vacuum chamber, and the particle trajectories are recorded with a microscopic telescope and a high-speed camera. The dust samples are prepared as a mixture of particles with sizes from several micrometers to approximately 90.0 μm in radius. In addition, a polyimide tape with the adhesive surface is placed around the dust sample to collect the lofted particles up to approximately 10.0 cm distance. The collected silica microspheres are studied under the microscope to measure the size variation over the distance from the dust source. The experiment results show that spherical particles and residues effortlessly reach up to 10 cm distance, whereas the fluffy dust aggregates are observed particularly near the dust sample. In addition, the analysis of trajectories shows that the dust grains accelerate rapidly to their launching velocities below 12.0 ms due to the repulsion between the neighboring dust particles. Finally, the peak of the dust launching angle distribution is determined to be around 43.5–45° from the surface normal.

DOI： 10.1016/j.asr.2021.03.037

その他リンク： https://www.sciencedirect.com/science/article/pii/S0273117721002623

An Overview of the BIRDS-4 Satellite Project and the First Satellite of Paraguay 査読有り

Adolfo Javier Jara Cespedes, Izrael Zenar Casople Bautista, BIRDS-4 Project Members, BIRDS Partners, George Maeda, Sankyun Kim, Hirokazu Masui, Takashi Yamauchi

35th Annual Small Satellite Conference 2021年06月

Sulphur‑fuelled Surface Arc Thruster for Propelling Nanosatellites 査読有り

Senior Shimhanda, Kotaro Hiraka, Taro Inoue, Kazuhiro Toyoda, Mengu Cho,

Advances in Astronautics Science and Technology 4 ( 4 ) 39 - 46 2021年06月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Pulsed electrothermal thrusters use kiloampere discharge currents for polytetrafluoroethylene (PTFE) ablation and sublimation. However, higher arc currents cause higher electromagnetic interference (EMI). A 10 J surface arc thruster (SAT), which adopts current regulating diodes (CRD), was developed that enables significant reduction in EMI. A CRD limits the discharge currents to 5 A in spite of the applied voltage. A low-melting-point sulphur propellant has been used that enables low-discharge currents to efficiently ablate it and accelerate it electrothermally. In this paper, the near-term potential for elemental sulphur propellant in SAT is investigated. The advantages of sulphur with respect to PTFE are presented. First, we measured the pulse width of the main discharge. Then sulphur propellant proved superior to PTFE propellant in discharge duration. The mean pulse widths of PTFE and sulphur are 3.38 and 22.1 ms, respectively. Second, we measured the pressure rise in the vacuum chamber after each discharge. The mean pressure rises of PTFE, sulphur powder and sulphur solid are 0.43, 0.94 and 1.9 mPa, respectively. Sulphur powder experienced the least intensity of discoloration in comparison with other propellants. The discharge initiator misfired frequently during PTFE ablation, but it ignited successively during sulphur ablation. Experimental results indicate sulphur is a suitable propellant for surface discharge propulsion, and for low arc currents is superior to PTFE.

DOI： 10.1007/s42423-021-00074-5

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85160943424&origin=inward

Calibration of Magnetic Field Sensor Data Using Flight Results 査読有り

Withanage Dulani Chamika, Mariko Teramoto, Sangkyun Kim,

Global Space Exploration Conference (GLEX 2021) 2021年06月

Design on-board data processing for double Langmuir probe on lean satellite 査読有り国際誌

Suryana R., Tejumola T.W., Kim S., Cho M.

Journal of Physics: Conference Series 1876 ( 1 ) 2021年05月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The explosive growth of lean satellites (small/micro/nano/pico) has positioned this class of satellites as a unique tool for space science missions. Langmuir probe is one of the most frequently used payloads to achieve space plasma measurement missions because of their low requirement in terms of system development, size, and relatively low power requirements to drive the mission. Double Langmuir probe can overcome the limitations of a single Langmuir probe measurement as reference ground in the satellite is not required. The limitation of data communication speed is one of the problems that always occur in the development of a multi-mission lean satellite. Data communication speed can be improved by using another system such as S-band or X-band, but those will be required for high power consumption. One of the solutions is the reduced size of the data by using on-board data processing on satellites. On-board data processing aims to improve data communication speed when sending DLP data to ground stations and how to determine plasma parameters. On-board data processing for a double Langmuir probe will be calculated electron temperature and electron density by using Raspberry PI zero. On-board data processing aims to reduce the size of data so that the time of transmission between satellite and ground stations will be shorter. On-board data processing can be a pragmatic solution because processed data only contains useful information according to user requirements.

DOI： 10.1088/1742-6596/1876/1/012025

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Programmable Interface Board for Higher CubeSat Form Factor and Complex Mission Payload 査読有り

Marloun Sejera, Takahashi Yamauchi, Yukihisa Otani,

2021 CubeSat Developers Workshop 2021年04月

Quantitative Evaluation of SRS Similarity for Aerospace Testing Applications 査読有り国際誌

Ibukun O. Adebolu , Hirokazu Masui , Mengu Cho

Shock and Vibration ( Hindawi ) 2021 2021年02月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The similarity between a shock response spectrum (SRS) and a target shock specification is essential in evaluating the success of a qualification test of a space component. Qualification testing facilities often utilize shock response databases for rapid testing. Traditionally, the comparison of two shocks (SRS) depends on visual evaluation, which is, at best, subjective. This paper compares five different quantitative methods for evaluating shock response similarity. This work aims to find the most suitable metric for retrieving an SRS from a pyroshock database. The five methods are the SRS difference, mean acceleration difference, average SRS ratio, dimensionless SRS coefficients, and mean square goodness-of-fit method. None of the similarity metrics account for the sign of the deviation between the target SRS and database SRS, making it challenging to satisfy the criteria for a good shock test. We propose a metric (the weighted distance) for retrieving the most similar SRS to a target SRS specification from a shock database in this work. The weighted distance outperforms the mean square goodness-of-fit and other metrics in database SRS retrieval for rapid qualification testing.

DOI： 10.1155/2021/6655878

その他リンク： https://www.hindawi.com/journals/sv/2021/6655878/

Adaptive Array Antenna in Ground Station Control System for Massive LEO CubeSat Constellation Tracking 査読有り国際誌

Syazana Basyirah Binti Mohammad Zaki, Mengu Cho, Nobuyuki Kaya

International Review of Aerospace Engineering ( Praise Worthy Prize ) 14 ( 2 ) 97 - 111 2021年02月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Since Low Earth Orbit has become a popular orbit to place satellites, CubeSat constellation tracking is challenging. The higher capacity and capability of a new Ground Station tracking system are in demand and this motivates researchers to come out with a solution to mitigate the traditional Ground Station degradation performance. This paper discusses the implementation of the Least Mean Square algorithm to the Adaptive Array Antenna for the Ground Station tracking system application. The simulation results show the main beam pattern’s capability to perform instantaneous tracking and steering towards the targeted CubeSat while suppressing the side lobes towards the other interfering CubeSats when massive CubeSats constellations take place. Planar and circular array antennas are analyzed by setting the optimum weighting factors to be adapted. Three scenarios of CubeSats constellations are simulated. The Adaptive Array Antenna’s performance for each scenario is analyzed based on the beam width characteristics and the Signal-to-Interference Ratio of the beam pattern. The number of CubeSats tracked by the Adaptive Array Antenna and the system’s capability to perform fast tracking as the number of antenna array elements is also discussed in this paper. Finally, solutions to mitigate the Least Mean Square algorithm’s limitation to perform fast tracking when massive interferer CubeSats are nearby are proposed.

DOI： 10.15866/irease.v14i2.19596

その他リンク： https://www.praiseworthyprize.org/jsm/index.php?journal=irease&page=article&op=view&path%5B%5D=25044

Universal Verification Platform and Star Simulator for Fast Star Tracker Design 査読有り国際誌

Victor Hugo Schulz, Gabriel Mariano Marcelino, Laio Oriel Seman, Jeferson Santos Barros, Sangkyun Kim, Mengu Cho, Gabriel Villarrubia González, Valderi Reis Quietinho Leithardt, Eduardo Augusto Bezerra

Sensors ( Multidisciplinary Digital Publishing Institute ) 21 ( 3 ) 1 - 23 Article number 907 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Developing star trackers quickly is non-trivial. Achieving reproducible results and comparing different algorithms are also open problems. In this sense, this work proposes the use of synthetic star images (a simulated sky), allied with the standardized structure of the Universal Verification Methodology as the base of a design approach. The aim is to organize the project, speed up the development time by providing a standard verification methodology. Future rework is reduced through two methods: a verification platform that us shared under a free software licence; and the layout of Universal Verification Methodology enforces reusability of code through an object-oriented approach. We propose a black-box structure for the verification platform with standard interfaces, and provide examples showing how this approach can be applied to the development of a star tracker for small satellites, targeting a system-on-a-chip design. The same test benches were applied to both early conceptual software-only implementations, and later optimized software-hardware hybrid systems, in a hardware-in-the-loop configuration. This test bench reuse strategy was interesting also to show the regression test capability of the developed platform. Furthermore, the simulator was used to inject specific noise, in order to evaluate the system under some real-world conditions.

DOI： 10.3390/s21030907

その他リンク： https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7866273/

Over-the-Air Firmware Update for an Educational CubeSat Project 査読有り国際誌

Maisun Ibn Monowar, Mengu Cho

International Review of Aerospace Engineering ( Praise Worthy Prize ) 14 ( 1 ) 20 - 27 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The CubeSat standard has been envisioned to teach students about satellites from the initial conceptualization to the in-orbit operation. Educational satellite projects have contributed to the creation of skilled workforce and have also advanced spacecraft technology. Unfortunately, educational satellites are not always successful. Design defects in the hardware can be isolated and addressed by running functional checks before launch. On the other hand, software bugs are difficult to identify and may go unidentified months into in-orbit operation. Due to the limited time available for software testing, students cannot spend sufficient time running the satellite software in an operational scenario. While in-orbit software patching is quite a simple and routine task for traditional commercial and government satellite operators, they are uncommon in the CubeSat domain. In this paper, the question of why satellite firmware updates are not very common for educational satellites is addressed. Technical necessities for an upgradable CubeSat are examined for both microcontroller and system-on-a-chip based CubeSats. After comparing both systems, a hybrid system is proposed as a solution for educational CubeSats. A system capable of upgrading the satellite firmware in a single satellite pass is synthesized. It is found out that a roadblock to over-the-air software updates for CubeSats is created not only by the technical aspect, but also by the students’ habit of skipping some engineering practices in their design process. Although their actions may not be critical to the mission success, they are much more important when a maintainable satellite firmware is desired. This paper explores the challenges in upgrading CubeSat flight software in orbit, some possible ways to implement this functionality, demonstration of a method that will allow in-orbit software updates despite having low resources, and a few recommendations for a maintainable satellite software.

DOI： 10.15866/irease.v14i1.19832

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Application of Small Satellites for Low-Cost Remote Data Collection Using LoRa Transmitters 査読有り

LEPCHA Pooja, KIM Sankyun, MASUI Hirokazu, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( 一般社団法人日本航空宇宙学会 ) 19 ( 2 ) 224 - 230 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The advancement of small satellites has greatly reduced the overall cost and development time of the satellite compared to conventional satellites fulfilling similar missions. Although there have been many developments on the satellite side, for missions like remote data collection the sensor nodes on the ground have been insubstantial because of its limitations in standalone operability and higher power consumption leading to higher cost and sparse area coverage. In this paper, we designed and developed a low power, low-cost remote sensor station with LoRa transmitters, which has the standalone operating capability. It is compact, mobile and it has a simple design. It is equipped with a self-sustaining power supply, LoRa transmitters, processors, antenna and sensors; mainly focusing on the weather monitoring parameters like humidity and temperature. The basic mechanism of data relay is to sense and transmit sensor data packets in real-time. The feasibility of the sensor station has been studied in terms of power budget, link budget, its operation outdoors and the overall development costs. The sensor station can be placed in areas where there are no ground infrastructures for communication.

DOI： 10.2322/tastj.19.224

その他リンク： https://ci.nii.ac.jp/naid/130007994902

Educational and Research Activities of Nanosatellite Technologies at the Kyusyu Institute of Technology 査読有り国際誌

Mariko Teramoto, Mengu Cho, Hirokazu Masui, Sangkyun Kim, Takashi Yamauchi, Necmi Chihan Orger, George Maeda

43rd COSPAR Scientific Assembly 2021年01月

Comparison of Propulsion Method for Regolith Thruster 査読有り国際誌

Noruji MUTO, Necmi Cihan ORGER, Jose Rodrigo CORDOVA ALARCON, Kazuhiro TOYODA, Mengu CHO

43rd COSPAR 2021 2021年01月

Deploying a Small Satellite-based Network of Ground Sensor Terminals (GSTs) in Developing Nations for enabling Remote Internet of Things (IoT) 査読有り国際誌

Lepcha P., Dayarathna T., Orger N.C., Purio M.A., Kishimoto M., El-Megharbel H.A., Cho M.

Proceedings of the International Astronautical Congress, IAC B4 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Small satellites are appealing platforms to develop and demonstrate new technologies at a lower cost and shorter development time. These small satellites in the low earth orbit (LEO) have relatively low propagation delay and provide global coverage while they are significantly suitable for Internet of Things (IoT) based applications in remote areas with no access to terrestrial communication networks. This paper describes overall mission architecture and implementation of remote IoT using a small satellite platform named KITSUNE. One of the missions is to leverage IoT for building a network of remote ground sensor terminals (GST) in 10 developing countries. The involvement in this network has enabled the emerging nations' access to space technologies using a cost-effective low-power GST for their preferred application. The collaboration has also promoted capacity building and upskilled the participants as they built their own GST for terrestrial measurements that could be uplinked to the satellite. In addition, this paper describes the receiver payload design capable of simultaneously receiving multiple data from 8 channels. To meet the constraints in overall size and power budget, LoRa modulation has been employed in communication between the GST and the onboard payload. Conclusively, the paper presents a feasibility study of the mission with communication tests performed on the ground between the satellite payload and GST. KITSUNE is expected to be launched in late 2021 or early 2022. The data collected by the satellite, specific for each country will be archived and analyzed for generating prediction profiles and monitoring variables as a basis to address local issues faced in these countries.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85127552199&origin=inward

DEMONSTRATION OF WILDFIRE DETECTION USING IMAGE CLASSIFICATION ONBOARD CUBESAT 査読有り国際誌

bin Azami M.H., Orger N.C., Schulz V.H., Cho M.

International Geoscience and Remote Sensing Symposium (IGARSS) 2021-July 5413 - 5416 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In the past decade, a massive number of wildfire events have been reported worldwide. An economic loss every year shows the importance of having satellites to overcome this catastrophe. Earth observation CubeSat can be a solution to detect, monitor, and provide data for the fire departments from the aerial view. For this purpose, the utilization of the deep learning (DL) algorithm to process the images captured onboard CubeSat before they are downlinked to the ground station is demonstrated. As a proof-of-concept, a single-board computer (SBC), Raspberry Pi, has been integrated into the KITSUNE 6U CubeSat to run the model. In this paper, the results of functional and environment tests of our proof-of-concept implementation have shown the feasibility of using image classification onboard the CubeSat. The DL algorithm's accuracy has reached 95% in the ground test, and this accuracy can be improved with further verifications of the platform and analysis of flight results. Therefore, DL's advancement in CubeSat is the state-of-art that can contribute significantly to address the wildfire issues.

DOI： 10.1109/IGARSS47720.2021.9553108

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85126019681&origin=inward

WILDFIRE DETECTION CUBESAT BASED ON CONVOLUTION NEURAL NETWORK 査読有り国際誌

Bin Azami M.H., Orger N.C., Schulz V.H., Cho M.

Proceedings of SPIE - The International Society for Optical Engineering 11914 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Wildfires burn millions of hectares of land every year globally. Most of them are caused by humans, while only 10-15% occur naturally due to the climate change. The hotter weather dries out forests and plants, making them more prone to fire. The "frontline wildfire defense" has fully utilized satellite imagery to monitor, map, and control the fire spread and damage. However, there are three major challenges of using traditional satellite data: (1) the spatial resolution, (2) the temporal resolution, and (3) the downlink and analyzing data on the ground. In recent technology, the satellites are developed into small-size CubeSats that supporting the resolution issues. By exploiting the deep learning (DL) technique, the CubeSat can become sufficiently "intelligent" to detect wildfire events. This paper discusses a potential approach for implementing a Convolution Neural Network (CNN) onboard a CubeSat to sense wildfire. The DL model has been tested on the Camera Controller Board (CCB) embedded with Raspberry Pi Compute Module (RPi CM3+), that interfacing with the imaging mission of a 6U CubeSat named KITSUNE. In addition, the space environment test of radiation Total Ionizing Dose (TID) with functional tests of the board has been discussed. The results have shown no anomaly observed on the RPi while the DL model achieved a 94% overall accuracy with 16 minutes of learning time and 32 seconds of classification time. Hence, the state-of-art processing images onboard CubeSat will improve the valuable downlink data as the limited time window passes through the ground station.

DOI： 10.1117/12.2603906

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85122980273&origin=inward

VERIFICATION OF THE 1U STANDARD CUBESAT ELECTRICAL POWER SYSTEM (EPS) FOR THE INTERNATIONAL SPACE STATION (ISS) SAFETY REQUIREMENTS 査読有り国際誌

Shrestha H.R., Purio M.A.C., Bautista I.Z.C., Cespedes A.J.J., Yamauchi T., Kim S., Cho M.

Proceedings of the International Astronautical Congress, IAC C3 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The BIRDS-4 satellites are the fourth generation of 1U CubeSats developed in Kyushu Institute of Technology (Kyutech), Japan. Kyutech has been deployed 1U CubeSats annually since 2017. It is called the BIRDS satellites series. BIRDS-4, a constellation of three 1U CubeSats, was released on 14th March 2021 from the International Space Station (ISS). The electrical power system (EPS) of BIRDS-4 needed to be modified to adopt the safety regulation changes that occurred after BIRDS-4. This paper explains how the satellites ensure the satellite's safety as required for satellites to be deployed from the ISS. This paper explains how the safety requirements for satellites were ensured from BIRDS-4, an additional deployment switch has been added to provide the three inhibits against the new cold launch requirement. This paper focuses on how deployment switches completely regulate the satellites by using inhibiting switches in the EPS circuit. Protection from over-charge, overdischarge, and external short hazards to the satellite's battery has been confirmed. Several ground tests were carried out for the BIRDS-4 Flight Model (FM) satellites, and the results of the verification are presented. Similarly, acceptance and verification tests were carried out for commercial-off-the-shelf (COTS) solar cells and batteries(cells). Inhibit verification test was conducted with the FMs by controlling 3 deployment switches that function as inhibit. To check the deployment switches actual functionality in the FM, inhibit functionality was also checked during the fit check. It was verified that the solar cells could not produce electricity inside the pod. The battery's charging line is completely isolated from the solar source by the electromechanical switches. The satellites were only being turned on 30 minutes after they have been deployed from the ISS. After going through the four generations of ISS deployment, the BIRDS EPS design now can serve as a standard 1U EPS design in compliance with ISS safety requirements.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85127553420&origin=inward

THE FIRST SATELLITES OF NEPAL, SRI LANKA (BIRDS-3); PARAGUAY (BIRDS-4); AND ZIMBABWE, UGANDA (BIRDS-5) 査読有り国際誌

Maeda G., Otim M., Ganda W., Cho M.

Proceedings of the International Astronautical Congress, IAC B4 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In 2015, Kyushu Institute of Technology (Kyutech) initiated a paradigm-shifting capacity building program called "BIRDS". First in 2015 was the BIRDS-1 Project, consisting of Ghana∗, Nigeria, Bangladesh∗, Mongolia∗, and Japan; second in 2016 was the BIRDS-2 Project, consisting of Bhutan∗, Malaysia, and the Philippines. (Note:∗denotes that BIRDS was the nation's first satellite.) The primary goal of BIRDS is capacity building. For any nation seeking a long-term, sustainable space program, it is sine qua non to have capable scientists and engineers. To promote space development, Kyutech identified "the first national satellite" as a means to capture the imagination and public support of non-space-faring nations. However, the first satellite is a means to an end - it is not the end. As the title of this paper indicates, Kyutech has progressed to BIRDS-3 (2017), BIRDS-4 (2018), and BIRDS-5 (2020), and has thus assisted more non-space-faring nations in building, launching, and operating, their first satellites. In this paper, we examine the impact of these CubeSat projects on each respective country. In each case, the goal is to kick off a sustainable national space program. Are these goals being achieved?

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85127539877&origin=inward

STORE AND FORWARD MISSION DESIGN IN BIRDS-4 SATELLITES 査読有り国際誌

Abbas Y.M.O., Sejera M., Bautista I.z., Cho M., Asami K.

International Geoscience and Remote Sensing Symposium (IGARSS) 2021-July 8030 - 8033 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

One of the most reliable and effective options to approach disaster-affected areas or remote places is to utilize the satellite-based solutions. The store and forward (SFward) mission is developed to leverage this concept. In BIRDS-4 SFward mission, the satellites collect data from ground sensor terminals that contain specific data needed by an application and store it to an internal memory. When one of the satellites passes over the main ground station, it forwards the stored data. This mission can also be used to broadcast announcements from ground centers to distributed receivers from the amateur community. This is most useful during disasters where conventional terrestrial networks are down. The mission is useful for transmitting data from remote areas without ground-based networks, allowing the collection of data from these remote sites. This can be utilized to achieve many applications.

DOI： 10.1109/IGARSS47720.2021.9553025

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85126067275&origin=inward

A TEMPORAL ANALYSIS OF THE RELATIONSHIP BETWEEN SYNOPTIC WEATHER STATION AIR TEMPERATURE MEASUREMENT AND SATELLITE-DERIVED LAND SURFACE TEMPERATURE: A CASE STUDY IN PORT AREA, MANILA CITY, PHILIPPINES 査読有り国際誌

Purio M.A.C., Cho M., Yoshitake T.

International Geoscience and Remote Sensing Symposium (IGARSS) 2021-July 4640 - 4643 2021年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

This paper aims to assess the relationship between atmospheric temperature and land surface temperature (LST) in Manila City using satellite and synoptic weather station data from 2014 to 2018. Manila is the capital and second-largest city of the Philippines and one of the most densely populated cities in the world, so it is important to analyze the said parameters to give a better picture of the city heat situation. Atmospheric temperature is taken from the synoptic weather station measurements at Manila Port Area while land surface temperature was derived from MODIS satellite data at the same point. By analyzing the data, trend changes of the parameters can be obtained and observed. Using statistical correlation analysis, the relationship between the parameters were also established. Data shows that high air temperature measurements fall between March and May. Correlation analysis shows that Temperature measurement from weather data (Min, Max, Mean) and derived values from satellite data (LST Day & Night) mostly have a high positive correlation.

DOI： 10.1109/IGARSS47720.2021.9553724

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85125992885&origin=inward

CubeSatNet: Ultralight Convolutional Neural Network designed for on-orbit binary image classification on a 1U CubeSat 査読有り

Maskey A., Cho M.

Engineering Applications of Artificial Intelligence 96 2020年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

A 1U CubeSat has severe limitations on size, power and downlink capabilities. Transferring images taken by imaging payload from orbit can be a challenging. To save time and effort in downlinking and post-processing, a mechanism must be in place to sort quality data before transmitting it to the ground station. This paper presents an innovative approach combining a novel CubeSat image dataset and a lightweight Convolutional Neural Network architecture for automatically selecting images for downlink on a 1U CubeSat. Coined as CubeSatNet, the neural network is trained on 60,000 augmented images, is tiny enough to run on an ARM Cortex MCU and is tested on on-orbit data from Kyushu Institute of Technology's BIRDS-3 CubeSats with an accuracy of 90% and F1 score of 0.92. CubeSatNet outperformed SVM, DBN and AE trained to classify CubeSat images. If implemented, the CNN could cut down operation time by about 2/3 while significantly improving the quality of received data.

DOI： 10.1016/j.engappai.2020.103952

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85090913715&origin=inward

Difference in Discharge Threshold Voltage between Electron Beam and Ultraviolet Environment 査読有り国際誌

Kazuhiro Toyoda, Takaaki Sasaki, Mengu Cho, Mitsuru Ohkubo, Kazuyoshi Seki

Journal of Spacecraft and Rockets ( American Institute of Aeronautics and Astronautics ) 58 ( 3 ) 619 - 627 2020年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

In the discharge ground tests of satellites, an electron beam is mainly used to simulate the electron environment on geostationary orbit; however, the insulator is charged on the orbit by photoelectrons by vacuum ultraviolet rays during sunshine. Discharge occurs when the insulator surface exceeds the discharge threshold voltage. Whether the discharge threshold differs between the electron beam and the vacuum ultraviolet ray was experimentally investigated using a solar array coupon. As a result, the discharge threshold voltage was lower by about 1 kV when using vacuum ultraviolet light rather than when it was charged by using an electron beam. It was assumed that the electron beam was bent by the electric field at the edge of the solar cell, making it difficult to be charged, and detailed surface potential measurements were performed. As a result, a difference was observed in the surface charge distribution between the electron beam and vacuum ultraviolet light, and it was found that when the electron beam was used, the solar cell edge was less likely to be charged.

DOI： 10.2514/1.A34880

その他リンク： https://arc.aiaa.org/doi/abs/10.2514/1.A34880?journalCode=jsr

HORYU-VI: International CubeSat Mission to Investigate Lunar Horizon Glow 査読有り国際誌

Necmi Cihan Orger, Mengu Cho, Omer Burak Iskender, Wee Seng Lim, Amal Chandran, Keck Voon Ling,King Ho Li Holden, Chee Lap Chow, John Bellardo, Pauline Faure, Fabio Santoni, Christian Circi, Paolo Marzioli, Federico De Grossi, Lorenzo Frezza, Kazuhiro Toyoda, Hirokazu Masui, Teramoto Mariko, Jose Rodrigo Cordova Alarcon, Takashi Yamauchi, Sangkyun Kim, Jian Wei Mark Lim, George Potrivitu, Matteo Laterza

71st International Astronautical Congress 2020年10月

Low-Thrust Trajectory Optimization for CubeSat Lunar Mission: HORYU-VI Trajectory 査読有り

Omer Burak Iskender, Sangkyun Kim, Keck Voon Ling, Mengu Cho, Necmi Cihan Orger

71st International Astronautical Congress 2020年10月

A Grid Square Statistical Approach in Data Organization for Urban Growth Impact Assessment on In-and-Outdoor Thermal Condition in Manila City, Philippines 査読有り国際誌

Mark Angelo C. Purio, Mengu Cho, Tetsunobu Yoshitake, Tsolmon Renchin

71st International Astronautical Congress 2020年10月

Remote Sensing Applied to the Study of the Triatomines Dispersion Dynamics, Case Study: Indigenous Communities of Paraguayan Chaco 査読有り国際誌

Adolfo Javier Jara Cespedes, Izrael Zenar Casople Bautista, Federico Augusto Gaona Veron, Antonieta Rojas de Arias, Mengu Cho

71st International Astronautical Congress 2020年10月

Sulphur-Fueled Surface Arc Thruster for Propelling Nanosatellites 査読有り国際誌

Senior Shimhanda, Kotaro Hiraka, Taro Inoue, Kazuhiro Toyoda,Mengu Cho

71st International Astronautical Congress 2020年10月

Ionosphere Measurement: Point-to-point Total Electron Content Estimation Using UHF Inter-Satellite Ranging for Cube-Sat Constellation 査読有り国際誌

Hoda Awny El-megharbel, Makiko Kishimoto, Necmi Cihan Örger, Victor Schulz, Tharindu Dayarathna, Rahmi Rahmatillah, Mariko Teramoto, Mengu Cho, Chee Lap Chow, Man Siu Tse and Holden Li,

71st INTERNATIONAL ASTRONAUTICAL CONGRESS 2020 2020年10月

CUBESAT INTERFACE STANDARDIZATION TO ACHIEVE FASTER DELIVERY AND MISSION SUCCESS 査読有り国際誌

Mengu Cho, Takashi Yamauchi, Marloun Sejera, Sangkyun Kim, Hirokazu Masui

71st International Astronautical Congress 2020年10月

SURVEY ON NANO-SATELLITE CAPACITY BUILDING NEEDS AROUND THE WORLD 査読有り国際誌

Mengu Cho, George Maeda, Yasuyuki Miyazaki, Yukihito Kitazawa, Michio Ozawa, Rei Kawashima

71st International Astronautical Congress IAC-20-B4.1.1.x59649 2020年10月

Improvement of Communication System for 1U CubeSat 査読有り国際誌

Makiko Kishimoto, Tharindu Lakmal Dayarathna Malmadayalage, Abhas Maskey, Pooja Lepcha, Dulani Chamika Withanage, Yuta Kakimoto, Yuji Sasaki, Hari Ram Shrestha, BIRDS Partners, George Maeda, Takashi Yamauchi, Sangkyun Kim, Hirokazu Masui, Mengu Cho

34th Annual Small Satellite Conference 2020年08月

CubeSat Electrical Interface Standardization for Faster Delivery and More Mission Success 査読有り国際誌

Mengu Cho, Takashi Yamauchi, Marloun Sejera, Yukihisa Ohtani, Sangkyun Kim, Hirokazu Masui

Small Satellite Conference SSC20-WKI-03 2020年08月

A lean satellite electrical power system with direct energy transfer and bus voltage regulation based on a bi-directional buck converter 査読有り

Juan J. Rojas, Mengu Cho, Yamauchi Takashi

Aerospace 7 ( 7 ) 94 2020年07月

Electrical Propulsion System Using Lunar Regolith Dust as Propellant 査読有り国際誌

Noruji MUTO, Necmi Cihan ORGER, Jose Rodrigo CORDOVA ALARCON, Kazuhiro TOYODA, Mengu CHO

JpGU-AGU Joint Meeting online 2020年07月

Development and Investigation of Communication Issues on a CubeSat-onboard Amateur Radio Payload with APRS Digipeater and Store-and-Forward Capabilities 査読有り

Adrian C. SALCES, Marloun P. SEJERA, Sangkyun KIM, Hirokazu MASUI, Mengu CHO

UNISEC Space Takumi J 9 ( 2 ) 17 - 46 2020年06月

hortening of the Delivery Time for University-Class Lean Satellite 査読有り国際誌

Kiran K. Pradhan, Mengu Cho

Journal of Small Satellites 09 ( 02 ) 2020年06月

Shortening of the Delivery Time for University-Class Lean Satellite 査読有り

Kiran K. Pradhan, Mengu Cho

Journal of Small Satellites 9 ( 1 ) 2020年01月

Survey on nano-satellite capacity building needs around the world 査読有り

Cho M., Maeda G., Miyazaki Y., Kitazawa Y., Ozawa M., Kawashima R.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The ministry of education of Japan (MEXT: Ministry of Education, Culture, Sports, Science and Technology) in 2019 awarded a research commission to Kyutech and UNISEC to investigate many aspects of nano-satellite capacity building around the world; the purpose of this research is to help the Government of Japan formulate its own future plans for this kind of capacity building. This study looked at not only capacity building activities of space faring countries, but also the space development situation (maturity) and their capacity building needs of non-space faring countries/regions. The study covered 52 non-space faring countries/regions in Asia, Middle East, Africa and Latin America. The paper covers the key findings made during the analysis of the survey.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85100929510&origin=inward

Implementation of Adaptive Antenna Array for Ground Station Tracking System 査読有り

MOHAMMAD ZAKI Syazana Basyirah, KAYA Nobuyuki, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( 日本航空宇宙学会 ) 18 ( 5 ) 199 - 208 2020年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

As the number of small satellites keeps increasing due to the low-cost development and fast delivery duration, there is a demand for higher capacity and capability of the ground station tracking system. Generally, the existing ground station tracking system faces major performance degradation while tracking satellites because of signals interference and multi-path fading. These problems motivate researchers to come out with interesting solution to mitigate the degradation performance. This paper describes the implementation of adaptive beam forming algorithm of phased array antenna for ground station tracking system. The adaptive antenna array demonstrates electronically self-steering radiation pattern capability towards satellites signals, suppress interferences and multi-path signals. This can be achieved by adapting the Least Mean Square (LMS) algorithm by varying the number and phase of the array antenna elements and the angle of beam steering to determine the Direction of Arrival (DOA) of incoming signals. The performance of adaptive LMS algorithm is investigated in MATLAB software by analyzing the radiation patterns for different number of array antenna elements, phases and beam steering angle. The purpose of LMS algorithm implementation in the Adaptive Array Antenna (AAA) system is to control weights adaptively, optimize the Signal to Noise Ratio (SNR) of the desired signal and minimize the Mean Square Error (MSE).

DOI： 10.2322/tastj.18.199

その他リンク： https://ci.nii.ac.jp/naid/130007896457

Cubesat interface standardization to achieve faster delivery and mission success 査読有り

Cho M., Yamauchi T., Sejera M., Kim S., Masui H.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In 2019, a new project to standardize the CubeSat interface started. Discussion has been made utilizing various gathering opportunities of the CubeSat community. A survey on the CubeSat interface has been distributed the CubeSat community to collect the satellite developers' experience and desires regarding the interface, and the CubeSat vendors' reality and desires. A research work to identify the difficulties associated integrating CubeSat components from different vendors is on-going. Initial finding suggests that clear definition of interface related information, especially the digital data communication, in the user manual is really needed. A table of content of the standard has been drafted, which is mainly made of four parts. (1) Interface among components, (2) Interface between CubeSat bus (platform) and mission payloads, (3) Document specification to describe the information related to component interface, (4)Document specification to describe the information related to CubeSat bus (platform) interface. The project aims at submitting a new work item proposal to ISO/TC20/SC14 in summer 2021 and publish the standard by 2024.

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A grid square statistical approach in data organization for urban growth impact assessment on in-and-outdoor thermal condition in Manila City, Philippines 査読有り

Purio M.A.C., Cho M., Yoshitake T., Renchin T.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Urban growth has been observed to be progressively increasing globally as the world's population tends to live in the cities and its surrounding areas. This change, the urban heat emergence for example, affects human living conditions. Results such as thermal discomfort, high prevalence of heat related health conditions, air pollution, increased water usage and energy demand for air conditioning is now receiving more attention. Because of this impact, it is of utmost importance to understand the cause and trends of urban growth in relation to the changes in thermal conditions. Once we understand the relationships between the factors mentioned, it will be possible to predict future trends and therefore assess their impacts before they even happen. This paper provides the use of world grid square statistical approach as a preliminary method in organizing the data to be used in urban growth impact assessment on in-and-outdoor thermal condition in Manila City, Philippines. This approach is aligned with the Japanese national standard for grid-square code (JIS X0410) which is extended for worldwide usage known as the World Grid Square Statistics. It is implemented by dividing the locale into small mesh based on latitudinal and longitudinal line with a fixed partition. With these small meshes representing a small area in the locale, parameters from different range of sources such as land surface temperature from remotely-sensed (satellite imagery), terrestrial data, population, energy consumption and weather data can be merged in the generated mesh grids. This method shall allow easy comparison of area characteristics without being affected by the change of administrative boundaries of towns, municipalities, and districts. In addition, the mesh grid shall serve as a basic boundary unit to provide additional statistical data in the future. Moreover, the proposed system shall allow ease in data linkage and data processing, mapping, data creation in each area, observation area definition and numerical unit in simulation. Once these data are organized in the mesh grids, matrix of values shall be inputs for statistical analysis of data and parametric inputs for predictive models using machine learning methods. Applying the approach in Manila City results to generating 4480 grids with maximum area of 0.02 sq. km and will consequently be populated with data for assessing the impact urban growth on in-and-outdoor thermal condition.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85100946689&origin=inward

Creating cubesat image database for machine learning based onboard classification for future missions 査読有り国際誌

Maskey A., Cho M.

Advances in the Astronautical Sciences 173 475 - 483 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

CubeSats have limited downlink capability and can be especially challenging while downlinking images. Onboard selection of images could save bandwidth and time. One method for selection is through machine learning. To train a model, dataset is required. However, no such dataset is publically available. The objective of this study is to create a database specific to CubeSat for on-orbit image classification which can be deployed in future missions. The paper presents three methods for data collection. Firstly, open data from Sentinel 3A is used to create nadir pointed images. Secondly, images from the International Space Station is utilized to create horizon images. Lastly, the dataset is supplemented by Kyushu Institute of Technology’s internal image database from HORYU and BIRDS satellite projects. Data conditioning and augmentation techniques are also provided to extend the dataset resulting into 15,000 images that can be labeled and used for training.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85111867088&origin=inward

Sulphur-fuelled surface arc thruster for propelling nanosatellites 査読有り国際誌

Shimhanda S., Hiraka K., Inoue T., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Pulsed electrothermal thrusters use kiloampere discharge currents for polytetrafluoroethylene (PTFE) ablation and sublimation. However, higher arc currents cause higher electromagnetic interference (EMI). A 10 J surface arc thruster (SAT), which adopts current regulating diodes (CRD), was developed that enables significant reduction in EMI. A CRD limits the discharge currents to 5 A in spite of the applied voltage. A low-melting-point sulphur propellant has been used that enables low discharge currents to efficiently ablate it and accelerate it electrothermally. In this paper, the near-term potential for elemental sulphur propellant in SAT is investigated. The advantages of sulphur with respect to PTFE are presented. First, we measured the pulse width of the main discharge. Then sulphur propellant proved superior to PTFE propellant in discharge duration. The mean pulse widths of PTFE and sulphur are 3.38 ms and 22.1 ms, respectively. Secondly, we measured the pressure rise in the vacuum chamber after each discharge. The mean pressure rises of PTFE, sulphur powder and sulphur solid are 0.43 mPa, 0.94 mPa and 1.9 mPa, respectively. Sulphur powder experienced the least intensity of discoloration in comparison with other propellants. The discharge initiator misfired frequently during PTFE ablation, but it ignited successively during sulphur ablation. Experimental results indicate sulphur is a suitable propellant for surface discharge propulsion, and for low arc currents is superior to PTFE.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85100945416&origin=inward

SS27 Radiation protection and monitoring experiment on-board a 1U CubeSat and its ground verification 査読有り国際誌

Murase T., Masui H., Cho M., Wei S.

Proceedings - IEEE International Symposium on Circuits and Systems 2020-October 2020年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Commercial-Off-The-Shelf(COTS) Integrated Circuits (ICs) are mostly sensitive to irradiations (e.g., protons, heavy-ions, etc.)in space, leading to various Single-Event Effects (SEEs). Among different SEEs, Single-Event Latch-up (SEL) is one of the most critical because it is detrimental and often damages ICs. This paper reports a circuit implementation that serves to provide protection for COTS ICs from SEL. The on-ground hardware verification on the basis of Californium 252 depicts that the circuit successfully cuts off the SEL current and subsequently resets the COTS IC. The reported circuit has been adopted in a 1U CubeSat that will be launched early 2020.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85109282438&origin=inward

Remote sensing applied to the study of the triatomines dispersion dynamics, case study: Indigenous communities of Paraguayan Chaco 査読有り国際誌

Cespedes A.J.J., Cho M., Bautista I.Z.C., de Arias A.R., Veron F.A.G.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The species distribution models allow finding suitable areas for the development of the disease vectors with a low sampling effort either in time or in costs. The objective of this work is to determine the spatial distribution of triatomines based on the use of entomological and environmental variables using remote sensing tools. To determine the distribution, two main variables have been considered: the environmental variables and the entomological variable (presence of Chagas disease vector in the indigenous communities). For environmental variables were used: mean NDVI, mean temperature, maximum temperature and mean rainfall, all these derived from satellite images. For the entomological variable a total of 110 points of presence of the vector have been taken through manual collect of insects and the use of a real time remote monitoring system for triatomine using traps with sensors wireless networking, this detection information is transmitted to the research centers through internet, which means that its use is limited to areas with cellular coverage. This work also presents a Store-and-forward mission as part of the BIRDS-4 satellite Project of Kyushu Institute of Technology to collect data from remote areas and expand the study area. As a result, a distribution model based on environmental variables has been obtained that predicts the suitable places for the studied triatomines to be present, being able to serve for the ecological and epidemiological surveillance of the indigenous communities at risk, generating early warning systems and serving as a support to the authorities for decision making. Likewise, the environmental variables suitable for the species have been compiled, considering the known points of presence, being able to cite a value of mean temperature around 20 C, a maximum temperature of 32 C, mean precipitation around 10 ml and NDVI values very close to zero, which corresponds to bare terrain or with little vegetation.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85100949172&origin=inward

Ionosphere measurement: Point-to-point total electron content estimation using UHF inter-satellite ranging for CubeSat constellation 査読有り国際誌

Elmegharbel H.A., Kishimoto M., Orger N.C., R-Schulz V., Dayarathna T., Rahmatillah R., Teramoto M., Cho M., Chow C.L., Tse M.S., Li H.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The ionosphere, which is the upper ionized layer of the atmosphere, affects the transmission of radio waves and causes degradation in the performance of satellite-based navigation, communication, and surveillance systems. Measurements by satellites are used to validate the numerical models of the ionosphere by estimating the total electron content (TEC) along the propagation path of the radio waves from satellite to ground. TEC is simply the total number of electrons along a ray path from a transmitter to the receiver. The delay experienced by a signal travelling in the ionosphere is proportional to the TEC along the signal path. Consequently, mapping the state of the ionosphere in real-time is an important scientific study for the dynamic nature of the ionosphere which would as well help in maintaining the accuracy of these radio-based systems. Various techniques to mitigate these ionospheric effects were developed in the past decades; a widely distributed network of global navigation satellite system (GNSS) receivers provides 3D distributions of the electron density in the ionosphere on the regional scales and its temporal fluctuations. A constellation of CubeSats can be used to estimate TEC along the UHF links between these satellites and a network of ground stations; the time delay of the propagating signals is used to derive a single value of TEC and hence multiple measurements of vertical and slant TEC can be used to derive a global map of the ionosphere. The advantage of using the UHF band is its higher vulnerability to ionospheric effects. This paper will propose the design requirements and hardware implementation and testing of a payload for a CubeSat used for signal timestamped reception using the UHF communication band in addition to on-board processing to derive TEC values between satellite and ground station. The development of this payload is part of Space Precision Atomic-clock TIming Utility Mission (SPATIUM) project which was proposed by Laboratory of Lean Satellite Enterprises and In-Orbit Experiments (LaSEINE) of Kyushu Institute of Technology, Japan in collaboration with Nanyang Technological University, Singapore to measure the electron density distribution using a constellation of intercommunicating Cube-Satellites equipped with a highly precise atomic clock in different LEO orbits and a network of ground stations. SPATIUM-I is currently in orbit down-linking signals to be processed in the ground station, SPATIUM-II is currently under development to demonstrate the on-board processing of Up-link signals to the satellite.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85100926473&origin=inward

Horyu-VI: International cubesat mission to investigate lunar horizon glow 査読有り国際誌

Orger N.C., Cho M., Iskender O.B., Lim W.S., Chandran A., Ling K.V., Holden K.H.L., Chow C.L., Bellardo J., Faure P., Santoni F., Circi C., Marzioli P., de Grossi F., Frezza L., Toyoda K., Masui H., Mariko T., Alarcon J.R.C., Yamauchi T., Kim S., Lim J.W.M., Potrivitu G., Laterza M.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Interaction with the solar wind and UV/X-ray irradiation can cause the lunar dust to be electrostatically charged and mobilized all around the Moon, and light scattering by this dust cloud can be observed over the lunar terminator. This phenomenon, which has also been called the lunar horizon glow (LHG), still remains unexplained. The LHG observations using conventional lunar probes have limited observation opportunities and do not cover varying space weather conditions in cislunar environment such as strong upstream plasma flow and micrometeoroid flux that could enhance the lunar dust presence in the exosphere. The nanosatellite “HORYU-6” specialized in LHG observations will be put into lunar orbit to detect the light scattering above the lunar terminator. The proposed payload will perform multi-spectral imaging to monitor the lunar horizon several minutes before orbital sunrise or after orbital sunset for light scattering analysis. We show that we can obtain scientific results of lunar and planetary exploration using CubeSat at low cost and in a short period of time, and contribute to the development of lunar and planetary exploration in the future. The spacecraft will be developed jointly with universities in Singapore, the United States and Italy under the supervision of Kyushu Institute of Technology, with the aim of launching the SLS-2 rocket in the second half of 2022. Together with its own scientific objectives, the HORYU-6 mission will demonstrate the low thrust trajectory optimization by utilizing electric propulsion system together with other novel embedded technology demonstrations such as atomic clock, deep space navigation and communication with CubeSats.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85100916419&origin=inward

Difference in threshold voltage of arc inception between electron beam and ultraviolet environment 査読有り国際誌

Toyoda K., Kose S., Sasaki T., Cho M.

AIAA Scitech 2020 Forum 1 PartF 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

As a charging method in ground experiments, an electron beam is often used to simulate high energy particles. In addition to this, a charging method using ultraviolet has been devised because charging by sunlight also occur in the space environment. Accordingly, ultraviolet were used for the discharge threshold measurement experiment of the solar cell, but the large difference of the threshold voltage was seen in two charging methods. The purpose of this research is to find out the cause of this large difference and to apply ultraviolet to charging and discharge experiment of space solar cell. We assumed that the charging potential of the cover glass edge of the solar cell was different in two charging methods and it caused the difference of the discharge threshold voltage. Therefore, we measured the surface potential focusing on the cover glass edge. In the experiment, a sample simulating the structure of the space solar cell was prepared and irradiated with ultraviolet or electron beam until the potential of the cover glass surface did not change overall. The surface potential of the cover glass edge at this time was measured with a contactless surface electrometer, and the results by two charging methods were compared. As a result, it was found that the surface potential at the cover glass edge was different in two charging methods. On the other hand, it was also found that measurement accuracy was low. We devised measurement method using Pockels effect which can measure potential directly or plan to improve measurement accuracy by improving sample because higher measurement accuracy is required to clarify the difference in charging.

DOI： 10.2514/6.2020-2012

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Peltier-based Thermal Testing (PeTT) Vacuum Chamber: Affordable Testing Facility for Lean Satellites 査読有り国際誌

Bonsu Benjamin, Hirokazu Masui, Mengu Cho

UNISEC Space Takumi Journal 8 ( 2 ) 11 - 38 2019年12月

Near-zero metamaterial inspired UHF antenna for nanosatellite communication system 査読有り国際誌

Alam T., Islam M., Cho M.

Scientific Reports 9 ( 1 ) 2019年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019, The Author(s). Epsilon-and-mu-near-zero (EMNZ) metamaterial structure inspired UHF antenna for nanosatellite has been proposed in this paper. The antenna consists of 3 × 2-unit cell array on the ground plane and a meander line radiating patch. Coaxial probe feeding technique has been obtained to excite the antenna. The meander line enables the antenna to resonate at lower UHF band and the metamaterial array is used to make the resonant frequency stable by reducing the coupling effect with metallic nanosatellite structure. The metamaterial structure exhibits EMNZ characteristics from 385 MHz to 488.5 MHz, which facilitates stable resonant frequency and higher antenna efficiency when embedded with nanosatellite structure. The proposed EMNZ inspired antenna has achieved measured impedance bandwidth (S 11 < −10 dB) of 14.92 MHz (391 MHz–405.92 MHz). The perceptible novelty of this paper is the development of EMNZ metamaterial that significantly improves the UHF antenna’s operating frequency stability as well as efficiency for low earth orbit nanosatellite communications.

DOI： 10.1038/s41598-019-40207-3

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Techniques for Repeatable Pyroshock Testing on an Air Gun Shock Machine for Lean Satellites 査読有り国際誌

18. Ibukun Oluwatobi ADEBOLU, Hirokazu MASUI, Isamu INOUE , Mengu CHO

90th Shock and Vibration Symposium 2019年11月

Store and Forward Data Collection Using Low-Cost Sensor Stations 査読有り国際誌

Pooja Lepcha, Mengu Cho

4th International BIRDS Workshop 2019年11月

Propose Strategy to Increase Capacity Development for Cubesat Thermal Vacuum Testing in Africa 査読有り国際誌

Bonsu Benjamin, Hirokazu Masui, Mengu Cho

8th International Conference on Space Science and Satellite Technologies Application 2019年11月

BIRDS-3 Satellite Project Including the First Satellites of Sri Lanka and Nepal 査読有り国際誌

Withanage Dulani Chamika, Mengu Cho, George Maeda , Sangkyun Kim , Hirokazu Masui , Takashi Yamauchi , Sanath Panawannege

70th International Astronautical Congress 2019年10月

Introducing Low-Cost Thermal vacuum Testing Facility for the emerging space program in African Universities in Africa 査読有り国際誌

Bonsu Benjamin, Hirokazu Masui, Mengu Cho

70th International Astronautical Congress 2019年10月

Status of Assembly, Integration, and Testing (AIT) Facilities for Satellite Testing in Africa 査読有り国際誌

Bonsu Benjamin, Hirokazu Masui, Mengu Cho

27th Workshop on Space Technology for Socio-Economic Benefit, UN/IAF Symposium 2019年10月

Feasibility Analysis of Optical Communication System for a Moon Orbiting CubeSat and Earth Station 査読有り

Femi Ishola, Mengu Cho

70th International Astronautical Congress 2019年10月

How Seven Emerging Nations Entered the Space Age via BIRDS Projects 1 through 4 査読有り国際誌

George Maeda, Mengu Cho, Hirokazu Masui, Sangkyun Kim, Takashi Yamauchi

70th International Astronautical Congress IAC-19 2019年10月

New star identification algorithm using labelling technique 査読有り国際誌

Kim S., Cho M.

Acta Astronautica 162 367 - 372 2019年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 IAA A new star identification algorithm is proposed for the attitude determination of a star sensor in the lost-in-space case, where prior attitude information is not available. The algorithm is based on a labelling technique, which uses label values to represent each group of stars. Using label values, multiple stars are simultaneously identified without repetition of search work. This labelling algorithm allows for a fast identification speed with efficiency, and provides the capability of more reliable identification by redundant confirmation. The proposed algorithm was verified by simulation study under various conditions.

DOI： 10.1016/j.actaastro.2019.06.007

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A Performance Comparison of Solid Propellants in Surface Arc Thruster: Sulfur and Teflon 査読有り国際誌

Senior Shimhanda, Kotaro Hiraka, Hiroaki Murakami, Kazuhiro Toyoda, and Mengu Cho,

36th International Electric Propulsion Conference 2019年09月

Anomaly Investigation using Telemetry Data of Horyu-2 for Single Event Latch-up 査読有り国際誌

Hirokazu MASUI, Yuzo TANAKA, Takahiro TOMIOKA, Hiroshi FUKUDA,Kyutech satellite project , Mengu CHO

UNISEC Space Takumi J. 8 ( 1 ) 1 - 10 2019年09月

Attitude Testing Platform in a Vacuum Environment for a Lean Satellite with an Electric Thruster 査読有り国際誌

Marcos Hernandez-Herrera, Phongsakorn Meemak, Hiroki Hisatsugu, Kotaro Hiraka, Jose Rodrigo Cordova-Alarcon, Sangkyun Kim, Kazuhiro Toyoda, Mengu Cho

Journal of Small Satellites (JoSS) 08 ( 02 ) 849 - 858 2019年09月

AOBA VELOX-IV: 2U CubeSat for the technological demonstration of lunar horizon glow mission 査読有り国際誌

Kim S., Orger N., Cordova-Alarcon J., Hernandez-Herrera M., Masui H., Yamauchi T., Toyoda K., Cho M., Duy Vu B., Vinh T., Seng L., Hiang C.

Acta Astronautica 161 328 - 337 2019年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 IAA AOBA VELOX-IV is a 2U-sized CubeSat that has been developed by the Kyushu Institute of Technology and Nanyang Technological University for the technological demonstration of a future lunar mission. Decades ago, Surveyor and Apollo programs reported light scattering observations on the horizon of the Moon; however, only a limited number of investigations were performed after the Apollo program to observe the lunar horizon glow (LHG). It is still unknown what conditions produce the light glow on the horizon of the Moon. The lunar mission of the AOBA VELOX project is planning to send CubeSats to the Moon and to capture images of the LHG on the lunar orbit while determining the conditions that can support light scattering above the lunar horizon. Before the satellites go into the lunar orbit, the necessary technologies must first be confirmed in Earth orbit. AOBA VELOX-IV was launched to low earth orbit via a JAXA Epsilon rocket in 18th January 2019. This paper explains the LHG mission first, and presents an overview of AOBA VELOX-IV, its payloads, technical issues, and the flight model.

DOI： 10.1016/j.actaastro.2019.05.046

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Guest Editorial Spacecraft Charging Technology 査読有り国際誌

Andersen A., Bodeau M., Cho M., Davis V., Dennison J., Donegan M., Ferguson D., Green N., Inguimbert V., Jun I., Lai S., Likar J., Minow J., Parker L., Roussel J., Toyoda K., Garrett H., Usui H.

IEEE Transactions on Plasma Science 47 ( 8 ) 3629 - 3630 2019年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 1973-2012 IEEE. This marks the seventh issue of the IEEE Transactions on Plasma Science dedicated to Spacecraft Charging Technology. The theme of this issue is based on the papers presented at the 15th Spacecraft Charging Technology Conference, Kobe, Japan, in 2018. The history of spacecraft charging goes back to the first Spacecraft Charging Technology Conference, sponsored by AFRL and NASA, that was held at the U.S. Air Force Academy, Colorado Springs, CO, USA, in 1978. The 15th Spacecraft Charging Technology Conference was hosted by the Japan Aerospace Exploration Agency (JAXA) and the Graduate School of System Informatics, Kobe University. It continues a tradition of international conferences on a ~2-year cycle. This conference, as well as each previous one in the series, was a great success. The topical discussions have greatly helped in making progress in the fields of spacecraft charging, spacecraft-plasma interactions, and related areas. At the end of the 15th Conference, the assembly agreed to request publication of the proceedings of the conference in the IEEE Transactions on Plasma Science and to encourage the submission of the papers presented at the conference to the Journal.

DOI： 10.1109/TPS.2019.2925231

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Analysis of Charging of the HTV-4 Based on On-Orbit Data 査読有り国際誌

Tsujita D., Okumura T., Kobayashi Y., Kasai T., Ohkawa Y., Koga K., Cho M.

IEEE Transactions on Plasma Science 47 ( 8 ) 3905 - 3914 2019年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 1973-2012 IEEE. After three H-II transfer vehicles (HTVs) had finished their mission to resupply the International Space Station (ISS), NASA requested data of the HTV's potential to evaluate the charging/discharging process that occurs when the HTV docks to the ISS. To measure these data, a new instrument was installed on the fourth HTV. This instrument allows us to measure the HTV-4 surface potential relative to the surrounding plasma, and is called advanced technology on-orbit test instrument for space environment-mini (ATOTIE-mini). The ATOTIE-mini observed the HTV's local potential in the orbit for more than one month. The measured potential during the HTV solo-flight phase varied between-30 and-60 V in sunlight and was about 0 V in eclipse conditions. The HTV's potential during the time when it was docked to the ISS followed the ISS's potential with an almost constant offset of about 10 V. The data measured by ATOTIE-mini are consistent with those measured by the floating potential measurement unit on the ISS, and thus are considered reliable. The HTV's potential level itself was acceptable for ISS. Note that the solar array panels can generate up to approximately 120 V, which is much larger than the absolute potential range in sunshine. We analyze the potential distribution on the HTV surface by a multi-utility spacecraft charging analysis tool, because ATOTIE-mini can only observe one point on the HTV surface. The analysis results are discussed with respect to the flight attitude.

DOI： 10.1109/TPS.2019.2920153

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Development of UiTMSAT-1: An approach to lean satellite concept 査読有り国際誌

Mohamad Rahim, S.N., Mustafa, S.N.K., Azami, M.H., Zaki, S.B.M., Enche A Rahim, S.A., Jusoh, M.H. Cho, M., BIRDS-2 Members

ASM Science Journal 12 ( Special Issue 2 ) 62 - 71 2019年08月

ESD Experiment Results on Ground Using Experiment Model of HORYU-IV 査読有り国際誌

Hiroshi Fukuda, Tatsuo Shimizu, Kazuhiro Toyoda, Mengu Cho

Journal of Spacecraft and Rockets Published Online:5 Aug 2019https://doi.org/10.2514/1.A34497 2019年08月

CubeSat bus interface with Complex Programmable Logic Device 査読有り国際誌

Tumenjargal T., Kim S., Masui H., Cho M.

Acta Astronautica 160 331 - 342 2019年07月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 IAA A standardized interface for different CubeSat missions is one of the keys to reducing costs and delivery time. A backplane interface approach, proposed by the University of Würzburg in Germany as UWE-3, was implemented in three CubeSat projects at the Kyushu Institute of Technology (Kyutech) to shorten the development and assembly times. The backplane approach also helped to reduce the risk of workmanship errors associated with the harness. However, changes to the proposed standard interface board were necessary in every CubeSat project, to comply with the mission requirements. To obtain more flexibility, especially for data connections, this work introduces a novel idea of a software-configurable bus interface with a backplane board. A Complex Programmable Logic Device (CPLD) was used instead of hardware routing so that we can reconfigure the bus interface by reprogramming the CPLD. The concept was validated by a functional test with a breadboard module. A radiation test verified that the selected CPLD has enough strength to survive total ionization doses of more than 2 years in low Earth orbit. A new backplane board with CPLD has been integrated into the engineering model of the fourth CubeSat project at Kyutech, the BIRDS-3 project, and system level verification has been conducted.

DOI： 10.1016/j.actaastro.2019.04.047

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A New Split Pitch Square Shape Metamaterial Absorber for X band Application 査読有り

Hoque A., Islam M.T., Azim R., Singh M.J., Mat K., Cho M.

International Conference on Space Science and Communication, IconSpace 2019-July 85 - 90 2019年07月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 IEEE. Metamaterial electromagnetic wave absorbers may provide perfect absorption over a significant range of electromagnetic spectrum. Microwave absorber for X-band application mostly unable to maintain high bandwidth with good absorption and require RF shielding in few applications. In this paper, design, simulation and measurements of a X band (8-12 GHz) metamaterial broadband absorber presented. The proposed absorber developed by following transmission line principle making pitch on each square arm with the split in edge and middle of the structure. The Square arm will steer electromagnetic (EM) resonance to acquire significant absorption (90%) and Double-Negative (DNG) metamaterial property to ensure perfect shielding for microwave signals. Proposed metamaterial absorber with DNG characteristics has potential application sector like microwave shielding, satellite remote sensing, dielectric property measurement of material etc.

DOI： 10.1109/IconSpace.2019.8905969

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Analysis of lifetime extension capabilities for CubeSats equipped with a low-thrust propulsion system for Moon missions 査読有り国際誌

Cordova Alarcon J., Orger N., Kim S., Cho M.

Acta Astronautica 160 558 - 571 2019年07月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

In this paper, we analyze the mission lifetime extension capability for a CubeSat smaller than 3U in a circular lunar orbit at a 100-km altitude, assuming the utilization of a state-of-the-art low-thrust electric propulsion system such as pulsed plasma thrusters with an impulse bit (Ibit)and velocity change (ΔV)below 60 μNs and 120 m/s, respectively. Because of the non-spherical gravity field of the Moon and its strong influence on low-altitude lunar orbits, a long orbital lifetime is achievable only within a set of stable orbits which mainly depends on initial inclination and right ascension of the ascending node (RAAN); moreover, as a piggyback on a main mission, the deployment of CubeSats in those stable orbits is not guaranteed. For this reason, we propose an orbit correction strategy whose performance is constrained to the initial orbital parameters of the CubeSat (i.e., inclination and RAAN), its solar power generation capacity, its attitude control strategy, and its propulsion subsystem features, such as the thruster Ibit and budgeted ΔV. By analyzing the required time to perform the orbit correction maneuvers to extend the orbital lifetime and the minimum altitude achieved throughout the mission lifetime of the spacecraft, we demonstrated that a one-year mission can be achieved within initial orbital inclination values greater than 65°. For unstable orbits bounded by initial orbital inclination values smaller than 65°, the orbit lifetime can also be extended from a few days to up to one year. Better performance with our proposed orbit correction strategy can be achieved by using an electric propulsion system featuring Ibit and ΔV values greater than 40 μNs and 80 m/s, respectively. Our results show the feasibility of performing any orbit correction maneuver for the enhancement of the mission lifetime of a CubeSat, expanding the performance capabilities of CubeSats to any mission in a lunar orbit by reducing the limitation of deploying them in unstable orbits.

DOI： 10.1016/j.actaastro.2018.11.040

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Demonstration of lean satellite (1U CubeSat) testing using PeTT vacuum chamber 査読有り

Bonsu B., Masui H., Cho M.

Proceedings of 9th International Conference on Recent Advances in Space Technologies, RAST 2019 959 - 966 2019年06月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2019 IEEE. There has been a high demand for low-cost thermal vacuum testing facility for Lean satellite (1U CubeSat) program in emerging space economies. Most often, CubeSat testing is performed in a complex and expensive thermal vacuum chamber equipped with for example shroud filled liquid nitrogen (boiling point is-195.7oC) for simulating the cold temperature environment as close to the cold heat sink of outer space in a simulated low pressure (>10-3 Pa) chamber environment. This paper introduces PeTT vacuum chamber as a low cost and easy access testing facility suitable for simulating cold temperature plateaus for performing a functional test of the internal subsystems of Lean satellite (1U CubeSat) functional test. Under ISO 19683: 'Design Qualification and Acceptance Test of Spacecraft and Units', the test requirement for cold temperature plateau is equal to-or more than-15oC. The PeTT vacuum chamber has been developed to achieve ISO 19683 test requirements. The PeTT vacuum chamber consists of a Peltier cooling device integrated inside a vacuum chamber. The Peltier cooling device consists of 4multi-stage Peltier elements sandwiched in-between a copper surface plate and water cooler has a mass of 3.4kg and size 152mm length × 127mm width × 40 mm height. The Peltier cooling device is targeted for performing 1U Cubesat functional test by conduction heat transfer. The Peltier cooling device has a total maximum exchange heat capability of 400W which runs by water cooling system and varying DC power supply. The vacuum chamber has an inner diameter of 55cm equipped with a rotary pump and diffusion pump to achieve a low pressure around 10-4 Pa. The main goal of this paper is to provide low cost and easy access testing technique for space activities in emerging space economies especially universities space research and development laboratories, to build their capacity in the installation and operation of a thermal vacuum testing facility. This paper provides details of the design and development of the PeTT vacuum chamber, cost, and results for testing 1U dummy CubeSat.

DOI： 10.1109/RAST.2019.8767775

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An experimental and theoretical study of spatial langmuir probe plasma system for a small lean satellite called ten-koh 査読有り

Bendoukha S., Tapia I., Okuyama K., Cho M.

International Review of Aerospace Engineering 12 ( 3 ) 131 - 140 2019年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Praise Worthy Prize S.r.l.-All rights reserved. Ten-Koh is a small lean satellite developed by Kyushu Institute of Technology which was launched in piggyback with GOSAT2 and KhalifaSat on 29thOctober 2018, at 13:08 Japan Standard Time through the H-IIA-202 rocket of Tanegashima space center of Japan, that exploits different progress techniques to accomplish less cost growth and rapid delivery. One of the significant primary mission of satellite is double Langmuir probe system, this process incorporates a ground-validated system to observe the LEO space plasma environment. Several approaches were developed to estimate plasma density by using the single probes which is more difficult to use in nanosatellite because of the high saturation current flow. Double Langmuir probes coated by gold were designed and tested in plasma chamber, where an RF source generates Xenon gas with a 1.05×10-2 Torr pressure and an average plasma density of 1010 to 1012 m-3 for subtracting the current flow between both installed probes. Numerous simulations and ground experiments were conducted using SLP and DLP to measure space plasma parameters as current-voltage characteristics, electron density and electron temperature. The ground outcomes plasma data of Ten-Koh satellite, which is 23 kg of mass and 50 cm hexagonal shape, were analyzed and compared with ground and orbital measurements probes data of the launched satellite (Horyu IV). Copyright © 2019 Praise Worthy Prize S.r.l.-All rights reserved.

DOI： 10.15866/irease.v12i3.15927

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Experimental investigation on silica dust lofting due to charging within micro-cavities and surface electric field in the vacuum chamber 査読有り国際誌

Orger N., Toyoda K., Masui H., Cho M.

Advances in Space Research 63 ( 10 ) 3270 - 3288 2019年05月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 COSPAR The charged dust particles can be mobilized electrostatically by the repulsion between the adjacent grains and the surface electric field due to the incoming electron current and the charge accumulation within the micro-cavities. In this study, the experimental results of the initial vertical launching velocities and the maximum dust heights are compared with the estimated values for the lofted spherical dust grains by the patch surface charging equations. Silica particles with the sizes between <6 and 45 µm in radius are loaded on a graphite plate, and they are exposed to the electron beam with 450 eV energy under 4 × 10 −3 Pa vacuum chamber pressure. During the first set of the experiments, the dust samples are tested without an initial compression process and an additional horizontal electric field. Second, the dust samples are compressed by two different weights in order to increase the packing density under approximately 780.7 Pa and 3780 Pa. Finally, the dust grains are placed between the two parallel aluminum plates to apply approximately 2000 V/m and 4800 V/m horizontal electric field. A high-speed camera is used to record the transportation of the dust grains together with a microscopic telescope, and the results point out that the patch surface dust-charging model estimations are in agreement with the first experiments. On the other hand, the dust particles from the compressed samples are lofted with higher velocities than the estimations, and the number of the dust lofting observations decreases significantly, which demonstrates the importance of the micro-cavities and the increased charging requirement to overcome the contact forces. When the horizontal electric field is present, the initial vertical launching velocities are measured to be lower than the other experiments, which can be attributed to the decreased charging requirement for the dust lofting as a result of inter-particle collisions and rolling motion. According to the experimental results, the electrostatic dust transportation can be controlled not only by the ambient plasma and the solar irradiation on the airless planetary bodies, but also by the surface properties such as the contact surfaces between the dust grains, the number of the micro-cavities related to the packing density, and the presence of the horizontal electric field contributing to the external forces by other particle motions.

DOI： 10.1016/j.asr.2019.01.045

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Design, Analysis and Testing of Monopole Antenna Deployment Mechanism for BIRDS-2 CubeSat Applications 査読有り国際誌

Zaki S., Azami M., Yamauchi T., Kim S., Masui H., Cho M.

Journal of Physics: Conference Series 1152 ( 1 ) 2019年03月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© Published under licence by IOP Publishing Ltd. This paper presents an approach to design a feasible and reliable monopole antennae deployment mechanism for CubeSat applications. Nano-satellite has faced problems in designing antennae deployment system due to space and deployment mechanism constraints. In BIRDS-2 CubeSat, the nichrome wire burning release mechanism was used when activated, it will be heated up and thermally cut through fishing line, allowing the two monopole antennas to be deployed on +Y board and at +Z axis direction of the satellite. These antennae involved amateur radio frequencies in UHF and VHF bands due to its low cost and high accessibility by the end users. The UHF frequency band was used for command uplink, mission, telemetry, and CW beacon downlink whilst the VHF frequency band was used specifically for APRS-DP/S&F-RDC mission for both uplink and downlink. In order to achieve the effectiveness of the BIRDS-2 CubeSat communication system agreed with the link budget estimation, the dimensions of antennae on the CubeSat structure depend on the required gain and operating frequency. The paper discusses detailed results of mechanical and electrical interfaces of the two monopole antennas deployment mechanism with the satellite body and the nichrome wire burning release mechanism analysis. The tests results of the mechanism were analyzed particularly on the deployment time and the nichrome wire temperature differences.

DOI： 10.1088/1742-6596/1152/1/012007

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A Dual-Port Circular Polarized S-Band Antenna for Nanosatellite Communication System 査読有り国際誌

Alam T., Tariqul Islam M., Cho M.

Journal of Physics: Conference Series 1152 ( 1 ) 2019年03月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© Published under licence by IOP Publishing Ltd. In recent years, the development of the nanosatellite is not for the just research purpose but commercial opportunities as well. The antenna is a very important part of the nanosatellite communication system. This paper presents an S-band circular polarized (CP) antenna for nanosatellite space mission communication system. The antenna is designed on Rogers 5880 substrate materials and the electrical dimension of the antenna is 0.39λ × 0.39λ × 0.03λ. The result shows that the antenna has a-10dB reflection coefficient bandwidth of 15.625%, 3dB axial-ratio bandwidths of 70MHz and peak gain of around 6.68dB.

DOI： 10.1088/1742-6596/1152/1/012003

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BIRDS-2: A Constellation of Joint Global Multi-Nation 1U CubeSats 査読有り国際誌

Azami M., Maeda G., Faure P., Yamauchi T., Kim S., Masui H., Cho M.

Journal of Physics: Conference Series 1152 ( 1 ) 2019年03月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© Published under licence by IOP Publishing Ltd. BIRDS-2, the second generation of the Joint Global Multi-Nation Birds (JGMNB) project is a constellation of 1U CubeSats from Laboratory of Spacecraft Environment Interaction Engineering (LaSEINE), Kyushu Institute of Technology, Japan. The BIRDS-2 project consists of three identical 1U built by a group of students from four nations; Japan, Malaysia, Philippines, and Bhutan. It consists of 6 missions; Camera, Automatic Radio Packet Service-Digipeater (APRS-DP), Store and Forward (S&F), COTS GPS, Anisotropic Magneto Resistance Magnetometer (AMR-MM), and detection of single-event latch-up (SEL). The objective of BIRDS-2 is to provide an opportunity to learn the entire satellite system cycle, to lay down the foundation of the sustainable space program, and to create international networks of the ground station to assist the infant space program of the participating country. A total of 11 members learns the satellite development in a lean concept of 30m radius of the work area. The paper will describe the bus system of the BIRDS-2 CubeSats and the development process throughout the one year and three months of the project timeline. Completion of BIRDS-2 flight models remarks the successful design of the CubeSats bus system and waiting for the launch and deploy from International Space Station (ISS) around 3rd quarter of this year.

DOI： 10.1088/1742-6596/1152/1/012008

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A Dual-Port Circular Polarized S-Band Antenna for Nanosatellite Communication System 査読有り国際誌

Alam T., Tariqul Islam M., Cho M

Journal of Physics: Conference Series 1152 ( 1 ) 2019年03月

BIRDS-2: A Constellation of Joint Global Multi-Nation 1U CubeSats 査読有り国際誌

Azami M., Maeda G., Faure P., Yamauchi T., Kim S., Masui H., Cho M.

Journal of Physics: Conference Series 1152 ( 1 ) 2019年03月

Electrostatic Discharge Threshold on Coverglass Used to Protect Solar Cells in the Low Earth Orbit 査読有り国際誌

Khan A., Minh N., Toyoda K., Cho M.

IEEE Transactions on Plasma Science 47 ( 2 ) 1445 - 1452 2019年02月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 1973-2012 IEEE. Coverglass has been widely used to cover the solar cells of solar arrays for space power generation. Coverglass with high antireflection is widely used to protect the solar arrays from performance deterioration due to irradiation of space ultraviolet, protons, electrons, atomic oxygen (AO), and so on. Along with these, thermal cycles and/or shock may accelerate the decay synergistically affecting the threshold voltage of electrostatic discharge (ESD) on the coverglass. In order to reveal the effect of aging due to AO interaction on the ESD threshold, several coverglass samples have been exposed to low earth orbit grade AO generated by the CO 2 laser on the ground. Later, both pristine and AO-exposed coverglasses have been irradiated by energetic electrons to generate artificial arcing (ESD) under high vacuum system. Statistical analysis and Weibull distribution confirm that the threshold voltage of ESD is lower on the aged coverglass than virgin.

DOI： 10.1109/TPS.2018.2885926

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Estimating sun vector based on limited in-orbit data 査読有り国際誌

Faizullin D., Hiraki K., Cho M.

International Review of Aerospace Engineering 12 ( 2 ) 101 - 108 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Praise Worthy Prize S.r.l.-All rights reserved. This paper introduces an attitude and orbit determination system, in particular a sun vector determination algorithm, for HORYU-IV nano-satellite by Kyushu Institute of Technology (Kyutech). Usually, nano-satellites cannot use sensors with high specs because of limited budget and onboard space. In order to achieve the required accuracy of attitude determination, estimation algorithms combining different sources of attitude information should be used. One of the HORYU-IV missions has required sun vector information. In order to detect the sun angle, six sun sensors, which have originally been designed and developed by the authors, and five solar panels have been used. However, due to the narrow field of view and to the saturation property of these sensors, the duration of sun detection is quite limited. At a non-detection period, a gyro sensor is used in order to propagate the attitude. However, the sensor has the bias error in its measured value. Hence, the Extended Kalman Filter has been used in order to estimate the sun vector and the bias error of gyro sensors. A simulation result shows that the algorithm can estimate the sun vector in 1deg accuracy.

DOI： 10.15866/irease.v12i2.16189

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真空アーク推進機（VAT-pi2）の鳳龍四号における軌道上実証査読有り

豊田和弘, アゲエバカテリーナ, 村上弥生, 福田大, 清水達夫, 鳳龍四号開発チーム, 趙孟佑

日本航空宇宙学会誌 ( 一般社団法人日本航空宇宙学会 ) 67 ( 5 ) 158 - 160 2019年01月

担当区分：責任著者記述言語：日本語掲載種別：研究論文（学術雑誌）

キューブサットなどの超小型衛星はその大きさから推進機を搭載することは難しいが，搭載できればミッションの幅が大きく広がる．また，宇宙ゴミにならないように25年以内にデオービットすることもルール化された．このような背景から固体推進剤を用いた真空アーク推進機（VAT-pi2）の開発を行ってきた．陰極である導電性の固体推進剤，陽極，コンデンサおよび電源からなる真空アーク推進機はその簡単な構造から小型化できロバストである．また低地球軌道に存在するプラズマと干渉することで点火装置なしで自発放電をすることが可能である．今回VAT-pi2の軌道上での動作試験を超小型衛星「鳳龍四号」で行った．300V発電太陽電池を電源として動作させている．また放電電流を計測できるオシロスコープを搭載しており，同時に放電の様子を撮影できるカメラも搭載されている．軌道上での実験の結果，VAT-pi2の放電を確認することができた．放電波形および放電画像の取得は引き続き行っていく．

DOI： 10.14822/kjsass.67.5_158

その他リンク： https://ci.nii.ac.jp/naid/130007642572

Evaluation of Electron-emitting Film for Spacecraft Charging Mitigation (ELFs Charm) 査読有り

TANAKA Atomu, MATEO VELEZ Jean-Charles, DADOUCH Sarah, OKUMURA Teppei, SAKAMOTO Kenji, IWATA Minoru, TOYODA Kazuhiro, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( 一般社団法人日本航空宇宙学会 ) 17 ( 1 ) 1 - 6 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

To protect a satellite from accidents due to spacecraft charging, Kyushu Institute of Technology (Kyutech) is developing a device called ELFs-Charm, which stands for ELectron-emitting Film for Spacecraft CHARging Mitigation. Electron emission from ELFs-Charm was already confirmed in Polar Earth Orbit in 2012 via flight experiment onboard HORYU-II. As a next step, we are considering the practical operation for spacecraft charging mitigation. The present emission level is not enough to increase the satellite potential. We focus our efforts on improving two properties, charging property and the emission threshold. The charging property is measured by how well the differential voltage between the ELFs-charm insulator surface and the satellite chassis increases. The emission threshold is measured by the differential voltage when the electron emission starts. This paper reports the laboratory experimental results to measure the two properties of various samples. The sample made of fluorin resin coating had a good combination of the charging property and the emission threshold that makes it possible to emit electron under realistic ambient electron current density in orbit.

DOI： 10.2322/tastj.17.1

その他リンク： https://ci.nii.ac.jp/naid/130007542851

Development of UiTMSAT-1: An approach to lean satellite concept 査読有り

Mohamad Rahim S., Mustafa S., Azami M., Zaki S., Enche Ab Rahim S., Jusoh M., Cho M.

ASM Science Journal 12 ( Special Issue 2 ) 62 - 71 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© Academy of Sciences Malaysia 2019. This paper presents the development of the UiTMSAT-1 nanosatellite and the approach towards a lean satellite concept. The lean satellite concept comes from extensive reports and discussions among many satellite developers and space players with the increased capability and technology in producing small satellites from the introduction of the CubeSat Project. The concept makes aware the importance of low-cost technology and fast delivery system of the satellite as compared with the traditional satellite development process. The UiTMSAT-1, which is the Universiti Teknologi MARA (UiTM)'s first nanosatellite, underwent the lean satellite concept and scheduled development in its BIRDS-2 project. A work breakdown structure was created to have a well-defined description of the divisions involved in the UiTMSAT-1 nanosatellite development. UiTM, as the stakeholder of Malaysia's team in the BIRDS-2 project contributed during the whole process including the installation of the UiTM ground station to track and monitor the nanosatellites. A brief anal ysis was presented based on the UiTMSAT-1's housekeeping data of approximately three months preliminary observations since its deployment into orbit.

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The role of CubeSats programs in workforce development for developing countries. 査読有り

Raphael T.T., Welsh C., Oluwatobi A.I., George M., Cho M.

Proceedings of the International Astronautical Congress, IAC 2019-October 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2019 by the International Astronautical Federation (IAF). All rights reserved. Benefits from the exploration and eventual applications of space technology are evident in all aspects of our lives on Earth; from earth observation, navigation, communication and innovative spin-offs in all areas of science and technology. Apart from the huge capital investment involved, access to these benefits in part require long term investment in high level education and infrastructural development. In the past, this has been an impediment for developing countries to access space and develop manpower in allied technological areas as expenditures on space programs in such countries may seem inappropriate because of the need for diverting resources from near-term social programs. Recently, this narrative is changing as many developing countries can access space and also develop essential manpower through CubeSat (1U: 10cm cubic, 1kg) programs which offers a cheaper and faster access to space. These programs have shown that long-term economic prosperity of any nation depends in part on investment in human capital development, the advancement of which requires scientific training as well as the use, and eventually the development of new technologies. This paper shall bring to the fore a comparative analysis of several CubeSat projects considering the different models, lessons learned and success stories from Africa, South America and South-East Asia that are providing great scientific impact with near-term benefits through applications such as environmental monitoring, disaster response, and telecommunications to posit a pathway for helping developing and emerging nations to develop their workforce thereby hastening national and regional technology development.

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Perovskite solar cell for space application 査読有り

Bautista I., Shuzhang Y., Ma T., Cho M.

Proceedings of the International Astronautical Congress, IAC 2019-October 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2019 by the International Astronautical Federation (IAF). All rights reserved. Satellite developers are continuously doing research on satellite energy sources that are efficient, lightweight and cheap than the current Silicon and triple-junction solar cells being used. The emergence of organic-inorganic metal halide Perovskite solar cells (PSC) which, have high specific power (kW/kg), achieved record power conversion efficiencies greater than 22% and cheap to manufacture, has attracted the attention of scientists for its possibility to replace silicon and triple junction solar cells. These factors make Perovskite solar cells viable candidates for space applications. To determine the feasibility of PSCs in space, samples were tested under simulated Low Earth Orbit (LEO) space environment such as thermal cycle, vacuum, vibration, total ionization dosage and electron radiation. Results showed that PSC has the ability to survive and work in space with thermal variation having the largest effect on the performance of the PSC.

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How seven emerging nations entered the space age via BIRDS Projects 1 through 4 査読有り

Maeda G., Cho M., Masui H., Kim S., Yamauchi T.

Proceedings of the International Astronautical Congress, IAC 2019-October 2019年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2019 by the International Astronautical Federation (IAF). All rights reserved. Operating on the basis that "one cannot learn how to build satellites by reading books", Kyushu Institute of Technology (Kyutech) launched its BIRDS Project in 2015 with Ghana, Bangladesh, Mongolia, Nigeria, and Japan. The main purpose was to help most of them launch their first satellites, and then somehow make satellite development sustainable in their own countries after the return of their students. Subsequently, Kyutech started BIRDS-2 in 2016, BIRDS-3 in 2017, and BIRDS-4 in 2018, involving the nations of Bhutan, Malaysia, Philippines, Nepal, Sri Lanka, and Paraguay. BIRDS-5 will start in October of 2019. In this paper we discuss the various capacity building results in these countries. We believe the seeds have been sown in these countries for sustained national space development via the activities of launching their first satellites - a crucial step. The seven nations who did (or are doing) their first satellites are: (1) Ghana, (2) Bangladesh, (3) Mongolia, (4) Bhutan, (5) Nepal, (6) Sri Lanka, and (7) Paraguay. Every nation participating in BIRDS pays its own way - there are no subsidies from Japan. They end up with their first space borne satellites but much more importantly they have engineers who know how to build a CubeSat.

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Feasibility analysis of optical communication system for a moon orbiting Cubesat and earth station 査読有り

Ishola F., Cho M.

Proceedings of the International Astronautical Congress, IAC 2019-October 2019年01月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2019 by the International Astronautical Federation (IAF). All rights reserved. Data return capabilities of nano-satellites in deep-space missions are limited by available radio frequency bandwidth, platform size, weight and power (SWaP) constraints. Laser communications offers orders of magnitude higher data rates and miniature transmitting components on these satellites. This paper presents a comprehensive optical system link design analysis of a 6-U Cubesat for a lunar orbit, 395,000km range with a compact, low-cost 40cm Telescope on Earth achieving 250Mbps Pulse Position Modulated downlink. The Cubesat optical communication payload features a 5Watts, 1550nm Solid State Laser and MEMS Steering Mechanism to provide beam pointing control. Reaction wheels are employed for the Cubesat attitude control. An annual link availability and outage estimation is evaluated for a fixed ground terminal in Fukuoka, Japan and the link performance is compared at different weather conditions.

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BIRDS-3 satellite project including the first satellites of Sri Lanka and Nepal 査読有り

Chamika W.D., Cho M., Maeda G., Kim S., Masui H., Yamauchi T., Panawannege S., Shrestha S.B.

Proceedings of the International Astronautical Congress, IAC 2019-October 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Copyright © 2019 by the International Astronautical Federation (IAF). All rights reserved. The Joint Global Multi-National Birds also known as BIRDS, is a multinational small satellite program led by Kyushu Institute of Technology (Japan). BIRDS program gives opportunity to non-space fairing nations to design, integrate, build, test, launch and operate their nation's first satellite. This paper focuses on BIRDS-3 which is the third batch under BIRDS program. BIRDS-3 is a constellation of three 1U CubeSats belonging to Japan (Uguisu), Nepal (NepaliSat-1: Nepal's first satellite) and Sri Lanka (Raavana-1: Sri Lanka's first satellite). BIRDS-3 has two members (students) from Nepal, three from Japan, and two from Sri Lanka and one from Bhutan. These students have been enrolled in Space Engineering International Course (SEIC) in Kyushu Institute of Technology. External dimensions of one satellite is 113.5mm x 100mm x 100mm and the weight is approximately 1.05kg. This constellation executes four missions: Imaging Mission (CAM), Attitude Determination and Control System mission (ADCS), LoRa Demonstration Mission (LDM), Software Configurable Backplane Board Mission (BPB). The CubeSats were deployed to the orbit on 17th June 2019 from International Space Station (ISS). After deployment CubeSats are being operated through BIRDS ground station network. This paper describes the background, missions, stakeholders and initial operational results after the deployment from International Space Station (ISS).

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Ionosphere observation and 3D mapping mission via CubeSat constellation; in-orbit operation results of the SPATIUM-I CubeSat 査読有り国際誌

Aheieva K., Rahmatillah R., Ninagawa R., Adebolu I.O., Kim S., Kakimoto Y., Nakayama D., Kishimoto M., Elmegharbel H.A., Yamauchi T., Masui H., Cho M., Lap C.C., Ying Z., Siu T.M., Holden L.K.H.

Proceedings of the International Astronautical Congress, IAC 2019-October 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

This paper will describe the progress in the SPATIUM satellite project, developed to do the global three-dimensional ionosphere mapping via CubeSat constellation equipped with an atomic clock and will show the result of the on-orbit operation of about 1 year of the first path-finder satellite SPATIUM-I. The SPATIUM-I satellite, launched in October 2018, validated the key technologies that are based on the clock-signal phase-shift sent from the satellite carried Chip-Scale Atomic Clock (CSAC). The satellite did the on-orbit demonstration of Chip Scale Atomic Clock (CSAC) as well as the evaluation of the signal time delay due to ionosphere and atmosphere. SPATIUM-I satellite on-orbit operation results will be presented. Knowing the precise satellite location and the signal delay from each satellite that transmits the signal with two UHF frequencies, by solving the inverse problem we can derive the ionosphere density and atmosphere water vapor. This data can be used to improve the accuracy of the earth and space weather forecast. This concept will then be implemented for the evaluation of Ionosphere Observation and Ionosphere 3D mapping via SPATIUM-II and SPATIUM-III projects. The SPATIUM project is under development by the Laboratory of Spacecraft Environmental Interaction Engineering (LaSEINE) of Kyushu Institute of Technology in collaboration with Nanyang Technological University, Singapore.

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Flexible radio-frequency identification (RFID) tag antenna for sensor applications 査読有り国際誌

Islam M., Alam T., Yahya I., Cho M.

Sensors (Switzerland) 18 ( 12 ) 2018年12月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 by the authors. In this paper, an inkjet-printed flexible Radio-Frequency Identification (RFID) tag antenna is proposed for an ultra-high frequency (UHF) sensor application. The proposed tag antenna facilitates a system-level solution for low-cost and faster mass production of RFID passive tag antenna. The tag antenna consists of a modified meander line radiator with a semi-circular shaped feed network. The structure is printed on photo paper using silver nanoparticle conductive ink. The generic design outline, as well as tag antenna performances for several practical application aspects are investigated. The simulated and measured results verify the coverage of universal UHF RFID band with an omnidirectional radiation pattern and a long-read range of 15 ft. In addition, the read range for different bending angles and lifetimes of the tag antenna are also demonstrated.

DOI： 10.3390/s18124212

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Performance analysis of an S-band antenna for nanosatellite payloads communication system 査読有り国際誌

Alam T., Islam M., Amanath Ullah M., Cho M.

Microwave and Optical Technology Letters 60 ( 11 ) 2817 - 2820 2018年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 Wiley Periodicals, Inc. The nanosatellite concept was born from the low-cost small satellite educational research activities that lead to the nanosatellite revolution. However, in recent years, the development of the nanosatellite is not for just research purpose but commercial opportunities as well. Antenna is very crucial part of the nanosatellite communication system that establishes communication between space to ground. In this paper, an S-band circular polarized (CP) antenna is presented and investigate the performance compatibility for nanosatellite space mission. The antenna was fabricated on 1.575 mm thick Rogers 5880 substrate material. The measured result shows that the antenna has a −10 dB reflection coefficient bandwidth of 1.64%, 3 dB axial-ratio bandwidths of 38 MHz and realized gain of around 5.58 dB at the resonant frequency. The antenna was integrated with 2 U nanosatellite structure and investigated the antenna performance.

DOI： 10.1002/mop.31492

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Design and compatibility analysis of a solar panel integrated UHF antenna for nanosatellite space mission 査読有り国際誌

Alam T., Islam M., Amanath Ullah M., Rahmatillah R., Aheieva K., Lap C., Cho M.

PLoS ONE 13 ( 11 ) 2018年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Copyright: © 2018 Alam et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. A compact UHF antenna has been presented in this paper for nanosatellite space mission. A square ground plane with slotted rectangular radiating element have been used. Coaxial probe feeding is used to excite. The rectangular slot of the radiating patch is responsible for resonating at lower UHF bands. One of the square faces of the nanosatellite structure works as the ground plane for the slotted radiating element. The fabricated prototype of the proposed antenna has achieved an impedance bandwidth (S11< -10dB) of 7.0 MHz (398 MHz-405 MHz) with small size of 97 mm× 90 mm radiating element. The overall ground plane size is 100 mm × 100 mm × 0.5 mm. The proposed antenna has achieved a gain of 1.18 dB with total efficiency of 62.5%. The proposed antenna addresses two design challenges of nanosatellite antenna, (a) assurance of the placement of solar panel beneath the radiating element; (b) providing about 50% open space for solar irradiance to pass onto the solar panel, enabling the solar panel to achieve up to 93.95% of power under of normal conditions.

DOI： 10.1371/journal.pone.0205587

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BIRDS Project as Platform to Develop and Deploy the First Satellites of Four South Asian Nations 査読有り国際誌

G. Maeda and M. Cho

69th International Astronautical Congress (IAC) 2018年10月

The UNISEC-Global New Vision 2030-ALL 査読有り国際誌

Rei Kawashima, Mohammed Khalil Ibrahim, Fabio Santoni, Mengu Cho, Klaus Schilling

69th International Astronautical Congress (IAC) 2018年10月

Challenges for CubeSats safety design and verification to do lean satellite development 査読有り国際誌

Mengu Cho, Takashi Yamauchi, Pauline Faure, Sangkyun Kim, Hirokazu Masui

69th International Astronautical Congress (IAC) 2018年10月

Design, Development, Testing and On-orbit Performance Results of a Low-cost Store-and-Forward Payload Onboard a 1U CubeSat Constellation for Remote Data Collection Applications 査読有り

Adrian C. Salces, Syazana Basyirah M. Zaki, Sangkyun Kim, Hirokazu Masui, Mengu Cho

69th International Astronautical Congress (IAC) 2018年10月

HORYU-IV FLIGHT RESULTS OF SPACECRAFT PLASMA INTERACTION EXPERIMENTS 査読有り国際誌

Hiroshi Fukuda, HORYU-IV Team, Hirokazu Masui, Minoru Iwata, Kazuhiro Toyoda, Mengu Cho

69th International Astronautical Congress (IAC) 2018年10月

Enhanced 3 dB AR beamwidth metamaterial antenna for nanosatellite payload communication system 査読有り国際誌

Alam T., Islam M., Cho M.

Electronics Letters 54 ( 19 ) 1104 - 1106 2018年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© The Institution of Engineering and Technology 2018 A compact dual-circular polarised metamaterial inspired antenna is proposed for nanosatellite payload communication. The antenna consists of two-layered stacked structure with a sandwich rectangular parasitic layer between two layers. Two double negative metamaterial cells. Two unit cells of DNG metamaterial structure are applied inside the pentagonal radiator to enhance 3 dB axial ratio (AR) bandwidth and beamwidth. Two orthogonal feedings are utilised to generate dual-circular polarisation (CP). The antenna achieves measured 710 MHz (3.06–3.77 GHz) of -10 dB impedance bandwidth with 160 MHz (3.02–3.18 GHz) and 210 MHz (3.05–3.26 GHz) of 3 dB AR bandwidth for port 1 and port 2, respectively. The 3 dB AR beamwidth of 165° for port 1 and 212° for port 2 is exhibited with an average realised gain of 5.15 dB. A 1U nanosatellite structure has been utilised to realise the antenna performance while operation in real-time environment.

DOI： 10.1049/el.2018.5717

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Ultra-wideband (UWB) Antenna Sensor Based Microwave Breast Imaging: A Review 査読有り

Md. Zulfiker Mahmud, Mohammad Tariqul Islam, Norbahiah Misran, Ali F. Almutairi, Mengu Cho

Sensors 9 ( 18 ) 2951 2018年09月

Microwave Imaging Sensor Using Low Profile Modified Stacked Type PIFA Antenna 査読有り

Mohammad Tariqul Islam, Md. Amanath Ullah, Touhidul Alam, Mandeep, Jit Singh, Mengu Cho

Antenna Technologies for Microwave Sensors 18 ( 9 ) 2018年09月

記述言語：英語掲載種別：研究論文（学術雑誌）

Microwave imaging is the technique to identify hidden objects from structures using electromagnetic waves that can be applied in medical diagnosis. The change of dielectric property can be detected using microwave antenna sensor, which can lead to localization of abnormality in the human body. This paper presents a stacked type modified Planar Inverted F Antenna (PIFA) as microwave imaging sensor. Design and performance analysis of the sensor antenna along with computational and experimental analysis to identify concealed object has been investigated in this study. The dimension of the modified PIFA radiating patch is 40 × 20 × 10 mm3. The reflector walls used, are 45 mm in length and 0.2-mm-thick inexpensive copper sheet is considered for the simulation and fabrication which addresses the problems of high expenses in conventional patch antenna. The proposed antenna sensor operates at 1.55–1.68 GHz where the maximum realized gain is 4.5 dB with consistent unidirectional radiation characteristics. The proposed sensor antenna is used to identify tumor in a computational human tissue phantom based on reflection and transmission coefficient. Finally, an experiment has been performed to verify the antenna’s potentiality of detecting abnormality in realistic breast phantom.

DOI： 10.3390/s18092949

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Ultra-wideband (UWB) antenna sensor based microwave breast imaging: A review 査読有り国際誌

Mahmud M., Islam M., Misran N., Almutairi A., Cho M.

Sensors (Switzerland) 18 ( 9 ) 2018年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Globally, breast cancer is reported as a primary cause of death in women. More than 1.8 million new breast cancer cases are diagnosed every year. Because of the current limitations on clinical imaging, researchers are motivated to investigate complementary tools and alternatives to available techniques for detecting breast cancer in earlier stages. This article presents a review of concepts and electromagnetic techniques for microwave breast imaging. More specifically, this work reviews ultra-wideband (UWB) antenna sensors and their current applications in medical imaging, leading to breast imaging. We review the use of UWB sensor based microwave energy in various imaging applications for breast tumor related diseases, tumor detection, and breast tumor detection. In microwave imaging, the back-scattered signals radiating by sensors from a human body are analyzed for changes in the electrical properties of tissues. Tumorous cells exhibit higher dielectric constants because of their high water content. The goal of this article is to provide microwave researchers with in-depth information on electromagnetic techniques for microwave imaging sensors and describe recent developments in these techniques.

DOI： 10.3390/s18092951

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BIRDS-1 CubeSat Constellation using Compact UHF Patch Antenna 査読有り

MD. SAMSUZZAMAN, MOHAMMAD TARIQUL ISLAM, SALEHIN KIBRIA, MENGU CHO

IEEE Access 2018年09月

Lunar dust lofting due to surface electric field and charging within Micro-cavities between dust grains above the terminator region 査読有り国際誌

Orger N., Cordova Alarcon J., Toyoda K., Cho M.

Advances in Space Research 62 ( 4 ) 896 - 911 2018年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 COSPAR It has been suggested that lunar dust grains can be transported by the electrostatic forces above the lunar terminator and produce the lunar horizon glow (LHG) by forward-scattering of sunlight. In addition, the recent experiments have shown that dust grains can be lofted in the vacuum chamber due to charging within micro-cavities by absorbing the emitted secondary electrons under the electron beam current (Wang et al., 2016; Schwan et al., 2017). In this study, the required charge within micro-cavities in order to separate dust particles from the lunar surface are estimated by using the surface electric field and the forces of gravity and contact. In addition, the maximum heights for dust grains are calculated by initial vertical launching velocity from the surface and the acceleration within the electron sheath against the gravity. The following calculations are performed for the particles with 0.1, 1 and 5 μm radius, and the variation of ambient plasma conditions are studied throughout solar wind data of CME passages on 8–13 February 1997, 1–3 May 1998 and 8–12 March 2012. Current balance method is used to estimate the surface potential, electric field and Debye length to investigate how the lunar dust particles are mobilized under the various conditions. First, strong negative surface potentials can be observed during the post-shock plasma passages, and it produces stronger electrostatic forces acting on the lofted dust particles. Second, submicron-sized dust particles are launched from the surface less frequently than the larger size grains due to the charging time. The height predictions of the dust grains with 5 μm radius are similar to the LHG observations of Surveyor mission, and the results suggest that the heights of micron-sized dust grains are controlled by the initial vertical launching velocity more than the surface electric field, unlike the smaller sized particles. Finally, strong electrostatic forces are not sufficient solely to loft the dust particles to higher altitudes since a charged dust requires accelerating for a proper time and distance in the electron sheath.

DOI： 10.1016/j.asr.2018.05.027

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A solar panel-integrated modified planner inverted F antenna for low earth orbit remote sensing nanosatellite communication system 査読有り国際誌

Alam T., Islam M., Amanath Ullah M., Cho M.

Sensors (Switzerland) 18 ( 8 ) 2018年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. One of the most efficient methods to observe the impact of geographical, environmental, and geological changes is remote sensing. Nowadays, nanosatellites are being used to observe climate change using remote sensing technology. Communication between a remote sensing nanosatellite and Earth significantly depends upon antenna systems. Body-mounted solar panels are the main source of satellite operating power unless deployable solar panels are used. Lower ultra-high frequency (UHF) nanosatellite antenna design is a crucial challenge due to the physical size constraint and the need for solar panel integration. Moreover, nanosatellite space missions are vulnerable because of antenna and solar panel deployment complexity. This paper proposes a solar panel-integrated modified planner inverted F antenna (PIFA) to mitigate these crucial limitations. The antenna consists of a slotted rectangular radiating patch with coaxial probe feeding and a rectangular ground plane. The proposed antenna has achieved a −10 dB impedance bandwidth of 6.0 MHz (447.5 MHz–453.5 MHz) with a smallsized (80 mm× 90 mm× 0.5 mm) radiating element. In addition, the antenna achieved a maximum realized gain of 0.6 dB and a total efficiency of 67.45% with the nanosatellite structure and a solar panel. The challenges addressed by the proposed antenna are to ensure solar panel placement between the radiating element and the ground plane, and provide approximately 55% open space to allow solar irradiance into the solar panel.

DOI： 10.3390/s18082480

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Establishing space activities in non-space faring nations: An example of university-based strategic planning 査読有り国際誌

Faure P., Cho M., Maeda G.

Acta Astronautica 148 220 - 224 2018年07月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 IAA In 2015, Kyushu Institute of Technology initiated the Joint Global Multi-Nation Birds Satellite (BIRDS) program. As of September 2017, young professionals from Bangladesh, Ghana, Nigeria, Thailand, Mongolia, Philippines, Malaysia, and Bhutan are being involved in BIRDS program. To help the young professionals acquiring the right tools and preparing them to successfully establish indigenous space activities, the space strategic planning project was established in February 2017. During the project, young professionals from Bangladesh, Ghana, Mongolia, and Bhutan were invited to think about the strategy their home country should be following in the next ten years to achieve their country's goals in terms of space sciences, engineering, and utilization, while respecting the country needs and constraints. In this paper, the efforts undertaken by the different young professionals are reported and the guidelines for each country space strategic planning are described. From this work, the authors aim at promoting space activities development in non-space faring nations and encouraging non-space faring nations to find their right strategy to achieve sustainable indigenous space activities despite the nation's constraints.

DOI： 10.1016/j.actaastro.2018.05.005

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Validation of double Langmuir probe in-orbit performance onboard a nano-satellite 査読有り国際誌

Tejumola T., Zarate Segura G., Kim S., Khan A., Cho M.

Acta Astronautica 144 388 - 396 2018年03月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 IAA Many plasma measurement systems have been proposed and used onboard different satellites to characterize space plasma. Most of these systems employed the technique of Langmuir probes either using the single or double probes methods. Recent growth of lean satellites has positioned it on advantage to be used for space science missions using Langmuir probes because of its simplicity and convenience. However, single Langmuir probes are not appropriate to be used on lean satellites because of their limited conducting area which leads to spacecraft charging and drift of the instrument's electrical ground during measurement. Double Langmuir probes technique can overcome this limitation, as a measurement reference in relation to the spacecraft is not required. A double Langmuir probe measurement system was designed and developed at Kyushu Institute of Technology for HORYU-IV satellite, which is a 10 kg, 30 cm cubic class lean satellite launched into Low Earth Orbit on 17th February 2016. This paper presents the on-orbit performance and validation of the double Langmuir probe measurement using actual on-orbit measured data and computer simulations.

DOI： 10.1016/j.actaastro.2018.01.016

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Satellite communication system for disaster response in Bhutan 査読有り国際誌

Dorji C., Faure P., Maeda G., Cho M.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2018 by the International Astronautical Federation (IAF). All rights reserved. Bhutan is considered to be highly vulnerable to multiple hazards of geophysical as well as hydrological nature. It has been observed during disasters in the past that the existing communication systems, which are terrestrial systems, are destroyed physically or overloaded rendering them useless for communication. Without communication links in times of disasters, it paralyses official responders and decision makers for mobilization of relief efforts to the affected areas. This research aims to propose a low cost, reliable and rudimentary satellite-based communication system in times of disasters to save lives and reduce damages to properties. The proposed system will establish communication links among official responders and different administrative units in real-time through text messaging using portable end user terminals with messages relayed by satellite. The paper identifies major system requirements and constraints that will be imposed on the system, various elements that make up the system and communication flow architecture. In particular, the design of satellite constellation is presented in detail. The analysis shows that a proposed mission requirement can be achieved with as few as 3 satellites each on 2 orbital planes, forming a constellation in Low Earth Orbit (LEO). The analysis also shows that a satellite constellation with an orbit inclination range of 20 to 55 and an altitude of 500 km and above can achieve the system requirements, leaving a leeway to choose piggybacking launch of satellites. Through this paper, the authors also intend for Bhutan to consider the proposed system for future space mission not only to benefit the country in disaster response but to consider as an opportunity in enhancing technical human resource capability in space science and technology in the country.

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BIRDS project as platform to develop and deploy the first satellites of four South Asian nations 査読有り国際誌

Maeda G., Cho M.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2018 by the International Astronautical Federation (IAF). The BIRDS Project of the Kyushu Institute of Technology (â€œKyutechâ€) in Japan has become famous in the small satellite academic community for assisting non-space-faring nations design, build, test, launch, and operate their first satellites - or their first university satellites. In this talk we focus on a particular region: South Asia. Using BIRDS-1, BIRDS-2, or BIRDS-3 as training platforms for space engineering students (graduate-school level), the nations of Bangladesh, Bhutan, Sri Lanka, and Nepal are doing their first satellites, or have done it already. There are several implications involved when a non-space-faring nation finally gets its first indigenous satellite into space. This talk will explore those implications. The central implication is that the students who build their nation's first satellite using the overseas facilities of Kyutech will be fully equipped (in terms of skills and know-how) to return to their respective nations and build the second satellite at home. This second satellite is supremely significant. Often heard at various international venues are grandiose plans by non-space-faring nations to establish â€œan indigenous and sustainable national space programâ€. These well-meaning efforts often do not succeed because the key ingredient is missing in such efforts: in-house engineers with requisite skills to design, build, and test, space-going hardware. We believe the â€œBIRDS Paradigmâ€ offers the solution to this common start-up failure among developing nations as it provides that crucial ingredient in a unique and novel way. To make this thesis manageable in one presentation, we limit the story to four countries of one compact region of the world.

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The UNISEC-global new vision 2030-all 査読有り国際誌

Kawashima R., Ibrahim M., Aslan A., Cho M., Steyn H., Schilling K.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2018 by the International Astronautical Federation (IAF). UNISEC-Global is an international non-profit, non-government organization, supported by the Local Chapters (LCs) around the world. UNISEC-Global was established in 2013 with the vision of supporting space engineering education worldwide and of establishing Local Chapters (LC) in 100 countries by 2020 in universities It has now consisting of 15 LCs and 30 Points Of Contacts (POCs). Since its establishment, it has maintained conducting core activities, like hands-on space education based on CanSat and CubeSat, as well as developments the space community needs,, such as standardisation of electrical subsystem interfaces or global ground station networks. In 2017, UNISEC-Global was accepted as a permanent observer in UNCOPUOS because of its contributions to the capacity building in space engineering. The observer status added a new dimension to the UNISEC-Global to the gained experience. The UNISEC-Global found that the time to revise its vision has come. The revised vision is â€œBy the end of 2030, let's create a world where university students can participate in practical space projects in all countries.â€ By this new vision, UNISEC-Global wants to make sure that â€œNo one will be left behindâ€. It can also be a driving force to implement the United Nation Sustainable Development Goals (SDGs) through the peaceful utilization of outer space and improve its contributions to thematic priority No. 7 of the UNISPACE+50. One of the main activities of UNISEC-Global which is the Mission Idea Contest (MIC) introduces the SDGs as required objectives for the proposed satellites missions. The implementation plan to realize the revised vision seems to be challenging. The present paper discusses the efforts that has been done so far to align the ongoing activities to achieve the revised vision and the challenges to realize it.

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The international dimension of outer space activities: Capacity-building in space law and policy for small satellite developers 査読有り国際誌

Balogh W., Cho M., Maeda G.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2018 by the International Astronautical Federation (IAF). In 2011, the United Nations/Japan Fellowship Programme Post-graduate study on Nano-Satellite Technologies (PNST) was launched as part of the Basic Space Technology Initiative (BSTI) under the United Nations Programme on Space Applications, implemented by the United Nations Office for Outer Space Affairs (UNOOSA). Since then, more than 80 international students have been studying at Kyushu Institute of Technology (Kyutech) under the PNST and Space Engineering International Course (SEIC). Master and PhD degree students receive hands-on training in the design, development, testing and operation of small satellites. Countries conducting space activities are required to adhere to certain regulatory and legal frameworks under which they have to authorize and supervise the space activities under their jurisdiction, including those of nongovernmental actors and universities. Space system designers and engineers need to be aware how this impacts their projects. For this reason, Kyutech has identified the need for capacity-building in space law and policy for small satellite developers. For the first time in 2017, a two-credit course (16x90 minutes) titled â€œThe International Dimension of Space Activities: Space Law and Policy for Small Satellite Developersâ€ was developed and taught to 37 international PNST/SEIC. Course participants were exposed to the most important concepts of national and international space law and policy and to relevant regulatory and legal frameworks applicable to small satellite activities. The course included group exercises to draft national space laws and policies, aiming to promote responsible practices for a safe, secure and sustainable space environment and to enable course participants to become active contributors to their countries national space ambitions.

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Project overview of SAPTIUM-I; a technology demonstration mission toward global three-dimensional ionosphere mapping via cubesat constellation equipped with an atomic clock 査読有り国際誌

Aheieva K., Rahmatillah R., Ninagawa R., Adebolu I., Kim S., Kakimoto Y., Yamauchi T., Masui H., Cho M., Lap C., Ying Z., Siu T., Holden L.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2018 by the International Astronautical Federation. Many satellites already measured ionosphere density in LEO region and still this information is not enough to create a global 3D ionosphere map. The ionosphere constantly fluctuates in a global scale, which is a complication in the process of its re-creation. To improve and validate ionosphere numerical models, measurements taken by the individual satellite are used. To measure the total electron content (TEC), and have higher spatial and temporal resolution, higher accuracy and lower cost in comparison to Global Navigation Satellite System (GNSS), we propose a CubeSat constellation. With 1000 satellites on the different orbital planes in LEO, we can have spatial resolution of 15 km and a temporal resolution of 30 minutes. And the electron density distribution will be known by the solving the inverse problem from many observation provided by the constellation. The first pathfinder satellite, SPATIUM-I, is under development and will be launched in 2018. SPATIUM-I will validate the key technologies that are based on the clock-signal phase-shift sent from the satellite carried Chip-Scale Atomic Clock (CSAC). The project is under development by the Laboratory of Spacecraft Environmental Interaction Engineering (LaSEINE) of Kyushu Institute of Technology in collaboration with Nanyang Technological University, Singapore. This paper will present the status of SPATIUM-I development and the overview of the follow-on projects, SPATIUM-II and SPATIUM-III.

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Horyu-IV flight results of spacecraft plasma interaction experiments 査読有り国際誌

Fukuda H., Masui H., Iwata M., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2018 by the International Astronautical Federation (IAF). All rights reserved. HORYU-IV is a 30cm cubic satellite with an approximate mass of 11kg. The satellite was successfully launched by a H-IIA rocket to an orbit of 575km altitude with 31Âºinclination on February 17, 2016. Since then, HORYU-IV has been conducting various flight experiments related to spacecraft plasma interaction. HORYU-IV implements HORYU-II, the previous satellite operated from 2012 to 2017, high voltage photovoltaic power generation technology and uses it to perform research on discharge phenomena. HORYU-IV's main mission is to acquire an arc current waveform by an onboard oscilloscope and capture its image by a camera triggered by the oscilloscope. In addition, HORYU-IV carries out scientific experiments on arc mitigation high voltage solar array, plasma measurement using a double Langmuir probe, vacuum arc thruster, photoelectron current measurement and polymer material degradation. HORYU-IV captured various discharge waveforms and images in space that can be categorized into several types. Ground experiments were carried out to compare the waveforms between the flight results and the ground results. The Double Langmuir probe was operated in space and its result was compared with the computer simulation results. Photoelectron emission yield was measured for several material for the first time in orbit. The overall results obtained in the past two and a half years from the spacecraft plasma interaction experiments will be presented.

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Design, development, testing and on-orbit performance results of a low-cost store-and-forward payload onboard a 1u cubesat constellation for remote data collection applications 査読有り国際誌

Salces A., Zaki S., Kim S., Masui H., Cho M.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2018 by the International Astronautical Federation. As a technology demonstration mission of the three-member 1U CubeSat constellation of the joint global multi-nation BIRDS-2 Project, the store-and-forward (S&F) mission aims to demonstrate the potential use of a 1U CubeSat constellation for collecting data from ground sensor terminals deployed in remote or isolated sites. The three CubeSats are the first university CubeSats of Bhutan, Malaysia, and the Philippines. Their onboard S&F payloads collect various sensor data from experimental ground terminals deployed in respective home countries. Although a CubeSat constellation is an attractive platform for the said application - due to its substantially simpler design, lower cost, and faster development time - it also presents many technical challenges such as tight size, power, and communication link budgets. In this paper, first, the design considerations and implementation of our onboard S&F payload are discussed. The said payload operates in the VHF amateur band and consists of mostly very low-cost commercial-of-the-shelf components. Sensor data uplink is done at 1200 bps and gathered data downlink at 9600 bps through the UHF communication subsystem. Then, the investigation and test results are presented, including link budget analysis, communication tests, antenna deployment tests, and space environment tests. Finally, the initial on-orbit performance results within one month of satellites' operation in space are tackled.

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Challenges for CubeSats safety design and verification to do lean satellite development 査読有り国際誌

Cho M., Yamauchi T., Faure P., Kim S., Masui H.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2018 by the International Astronautical Federation (IAF). All rights reserved. Every satellite, regardless of its size, mission, value, capability or any other nature, shall comply with safety requirements. This statement applies even to a 1U or less CubeSat. The recent diversity in the CubeSat launch options, however, has brought complication in satellite design and verification. The safety requirements differ among the launch vehicles. The difference is particularly significant between the rocket launch and the ISS release. Satellite developers need to consider how to adapt their design to various safety requirements and how to verify their compliance from the early stage of satellite development, even before they decide on the launch option. Kyushu Institute of Technology (Kyutech) has operated Centre for Nanosatellite Testing (CeNT) in Laboratory of Spacecraft Environment Interaction Engineering (LaSEINE) since 2010. Those satellites that employed commercial-off-the-shelf (COTS) CubeSat components available on Internet had many safety-related issues to be resolved. Kyutech itself has developed 12 satellites that were launched by rockets or released from ISS and experienced various issues related to safety. The safety issues encountered by various CubeSats for various launch options are reviewed. How they were resolved with are introduced with suggestions on how to minimize the troubles that delay the satellite delivery time.

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BIRDS-1 CubeSat Constellation Using Compact UHF Patch Antenna 査読有り国際誌

Samsuzzaman M., Islam M., Kibria S., Cho M.

IEEE Access 6 54282 - 54294 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2013 IEEE. BIRDS-1 satellites, a constellation of five identical 1U CubeSats, were designed, manufactured, assembled, integrated, and tested at LASINE Laboratory, Kyutech, Japan. Students from five nations (Japan, Ghana, Mongolia, Nigeria, and Bangladesh) collaborated to develop a number of CubeSats with coordinated ground coverage, named 'Joint Global Multi-Nation BIRDS,' or abbreviated as 'BIRDS.' To establish the downlink communication between satellite and Earth, an UHF patch antenna was utilized. Patch antennas offer an ideal solution to Cube satellite communication requirements due to their compact dimension and lightweight. However, the limited surface area available in CubeSats, conventional UHF and VHF patch antennas cannot be used. In this paper, a compact coaxial fed UHF (437.375 MHz) patch antenna system for 1U BIRDS-1 CubeSat (small satellite) is presented. The proposed antenna consists of a spiral meander line patch at the top side and partial ground plane another side of the substrate. A shorting pin has also been utilized to change the resonance to the required UHF band. For the intended 1U BIRDS-1 application, the goal is to mount on satellite body within a limited area of 1U BIRDS-1 satellite. The proposed antenna dimension ( 0.105λ × 0.047λ × 0.002 λ at 437.375 MHz) and characteristics are compatible with any CubeSat standard structure. A prototype of the antenna was developed with a 1.57-mm-thick single layer Roger's substrate having a relative permittivity of 2.2, and measured results are consistent with simulation. The proposed UHF antenna has integrated and tested with 1U BIRDS-1 satellite. Finally, the satellite was successfully launched on June 3, 2017, from the John F. Kennedy Space Center, the USA at Low Earth Orbit for earth observations, message relay, space environment, and technology demonstration through the International Space Station.

DOI： 10.1109/ACCESS.2018.2871209

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Ionosphere irregularity observation using reference signals from CubeSat constellation 査読有り

Rahmatillah R., Aheieva K., Cho M., Holden L.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2018 by the International Astronautical Federation (IAF). Ionosphere is a complex region which rapidly change over the time. The rapid fluctuation in the Ionosphere electron density leads to communication problems between space and the ground. The quality of communication depends on the Ionosphere condition which is especially hard to predict in the lower to mid-latitude (15 0 - 30 0 ) region of the Earth. The error range of this area associated with the navigation signal can vary from 15 to 35 meters in accuracy which start to fluctuate after the sunset in the local time. Global Navigation Satellite System provides the information to be used as ionosphere density monitoring. This information, generally in Total Electron Content (TEC) value is necessary to map the ionosphere condition in global scale. Recently small satellite constellation become an alternative for the ionosphere monitoring due to the lower cost and faster development time. Kyushu Institute of Technology is developing a 2U CubeSat, SPATIUM-I, in collaboration with Nanyang Technological University in Singapore. This satellite will do on-orbit demonstration of Chip Scale Atomic Clock (CSAC) as well as the evaluation of signal time delay. This paper will present the basic algorithm to derive the electron density 3D distribution from the SPATIUM Observation data. This concept will then be implemented for the evaluation of Ionosphere Observation.

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BIRDS Satellite Project as a Model for Capacity Building and International Cooperation towards Sustainable Space Program in Africa 査読有り

Taiwo Raphael TEJUMOLA, BIRDS Project Members, George Maeda, Sangkyun Kim, Hirokazu Masui, Mengu Cho

United Nations / South Africa Symposium on Basic Space Technology 2017年12月

CubeSat mission for ionosphere mapping and weather forecasting using chip-scale atomic clock 査読有り国際誌

Aheieva K., Rahmatillah R., Ninagawa R., Adebolu I., Masui H., Yamauchi T., Kim S., Cho M., Chow C., Tse M., Li K.

Progress in Electromagnetics Research Symposium 2017-November 761 - 766 2017年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2018 Electromagnetics Academy. All rights reserved. The project SPATIUM (Space Precision Atomic-clock TIming Utility Mission) presents a new technique for ionosphere mapping using a constellation of CubeSats equipped with Chip Scale Atomic Clock (CSAC) to provide real-time three-dimensional mapping of ionosphere plasma density at the altitudes of electron density peak (200 to 400km above the Earth). This paper describes the principle of the ionosphere mapping and total electron content (TEC) determination using satellite signal transmission with a dual-frequency and signal shift determination at the Ground Station using the same referenced CSAC clock. The paper also describes reasons of RF signal delays/shifting due to atmosphere and ionosphere plasma conditions. A 2U CubeSat, SPATIUM-I, is introduced as a platform. The future plans for the project expansion are also given.

DOI： 10.1109/PIERS-FALL.2017.8293237

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Initial Results from an In-Orbit High-Voltage Experimental Platform: HORYU-IV 査読有り国際誌

Shimizu T., Fukuda H., Su N., Toyoda K., Iwata M., Cho M.

IEEE Transactions on Plasma Science 45 ( 8 ) 1853 - 1863 2017年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 1973-2012 IEEE. HORYU-IV is a nanosatellite developed to conduct experiments on electrostatic discharges (ESDs) in real space environments. Testing in space is very important to confirm ground testing results, because it is difficult to fully simulate the comprehensive environment of space on the ground, to evaluate the effects of such things as satellite movements, plasma conditions, sunlight, and chamber walls. Conventionally, occurrence counters have been used for such in-orbit experiments to find threshold voltages. However, they cannot provide detailed information for example magnitudes and the location of each ESD. We became highly aware of this limitation through our HORYU-II experience (which only had an occurrence counter) and we designed HORYU-IV in order to overcome this limited data issue. The main challenge with HORYU-IV is the carrying of standard laboratory equipment, such as oscilloscopes and event-capture cameras, which have never been successfully used in space before. Such measurement instruments, with solar array sample coupons and a high-voltage source, were launched on this satellite and have successfully provided current waveforms and images of spark of light from ESDs from space. This experimental method has been commonly used in ground-based spacecraft charging experiments, but has never been used in orbit. Hence, our satellite became the world's first operational platform equipped with an oscilloscope and event-capture camera for high-voltage experiments in space. Three different shapes of current waveforms were observed, and the arcing locations from images captured in orbit were identified. We have proved the concept of the remote laboratory in orbit. The observed discharge conditions will be replicated on the ground and the feedback will improve the ground testing methodology.

DOI： 10.1109/TPS.2017.2688725

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Mission Results Analysis of High-Voltage Technology Demonstration Satellite HORYU-II 査読有り国際誌

Fukuda H., Toyoda K., Cho M.

IEEE Transactions on Plasma Science 45 ( 8 ) 1871 - 1879 2017年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 1973-2012 IEEE. In 2012, the high-voltage technology demonstration satellite HORYU-II which is a nanosatellite (30 cm 3 , 7 kg) was launched into polar earth orbit. It is known that high-voltage power generation above 200 V in low earth orbit induces discharging. The main mission of HORYU-II was to achieve high-voltage (more than 300 V) generation without discharge in space orbit, and it was successful. After the initial operation, HORYU-II malfunctioned due to the single event latch-up, and could not continue mission operation. On December 22, 2014, HORYU-II was revived and restarted mission operations until HORYU-II malfunctioned again (March 18, 2015). We performed three types of missions that were high-voltage generation modes, nominal TJ array discharge experiment modes, and film TJ array discharge experiment modes. Even if the satellite spent two years in orbit, HORYU-II could still generate around 350 V and the discharge rate on a nominal TJ array showed little change.

DOI： 10.1109/TPS.2017.2705726

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Toward lean satellites reliability improvement using HORYU-IV project as case study 査読有り国際誌

Faure P., Tanaka A., Cho M.

Acta Astronautica 133 33 - 49 2017年04月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 IAA Lean satellite programs are programs in which the satellite development philosophy is driven by fast delivery and low cost. Though this concept offers the possibility to develop and fly risky missions without jeopardizing a space program, most of these satellites suffer infant mortality and fail to achieve their mission minimum success. Lean satellites with high infant mortality rate indicate that testing prior to launch is insufficient. In this study, the authors monitored failures occurring during the development of the lean satellite HORYU-IV to identify the evolution of the cumulative number of failures against cumulative testing time. Moreover, the sub-systems driving the failures depending on the different development phases were identified. The results showed that half to 2/3 of the failures are discovered during the early stage of testing. Moreover, when the mean time before failure was calculated, it appeared that for any development phase considered, a new failure appears on average every 20 h of testing. Simulations were also performed and it showed that for an initial testing time of 50 h, reliability after 1 month launch can be improved by nearly 6 times as compared to an initial testing time of 20 h. Through this work, the authors aim at providing a qualitative reference for lean satellites developers to better help them manage resources to develop lean satellites following a fast delivery and low cost philosophy while ensuring sufficient reliability to achieve mission minimum success.

DOI： 10.1016/j.actaastro.2016.12.030

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Flight results of new technology onboard a lean satellite HORYU-IV 査読有り国際誌

Cho M., Fukuda H.

IEEE Region 10 Annual International Conference, Proceedings/TENCON 3439 - 3442 2017年02月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2016 IEEE. HORYU-IV is a 30cm cubic satellite with an approximate mass of 10kg. HORYU-IV carries a high voltage photovoltaic solar array capable of generating a voltage up to 350V. Its main mission is to acquire an arc current waveform by an onboard oscilloscope and capture its image by a camera triggered by the oscilloscope. In addition, it plans to carry out various flight demonstration of new technology. The satellite was successfully launched to an orbit of 575km altitude and 31 ° inclination on February 17, 2016 by H-IIA rocket. Overview of the satellite and its mission are presented.

DOI： 10.1109/TENCON.2016.7848693

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Solar array electrostatic discharge current and image captured in orbit 査読有り国際誌

Shimizu T., Fukuda H., Toyoda K., Cho M.

Journal of Spacecraft and Rockets 54 ( 2 ) 497 - 499 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

A study is conducted to demonstrate solar array electrostatic discharge current and image captured in orbit. The HORYU-4 high-voltage experimental system has five solar array coupons, which are two nominal solar arrays, two film-wrapped solar arrays, and a semi-conductive coating solar array. These coupons use commercially available multi-junction solar cells, and an electron collector. Three solar arrays are accommodated in the pitted area. This pocket is made to darken these coupons by shading from the sunlight and capturing visible discharge flash lights. In addition, the inside of the pocket is painted with black color coating to prevent sunlight reflection.

DOI： 10.2514/1.A33622

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Charging and discharging phenomena of plastic encapsulated microcircuits used in nanosatellites 査読有り国際誌

Khan A., Chen S., Cho M.

Journal of Spacecraft and Rockets 54 ( 2 ) 386 - 394 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Copyright © 2016 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Nanosatellites are generally used in low Earth orbits for diverse applications such as remote sensing, space weather monitoring, technology demonstrations, and even system engineering education. During their orbit lifetime, they often fly through the polar region and/or the South Atlantic Anomaly zone. Electrons at these regions are sufficiently energetic enough to penetrate into the thin aluminum exterior shield of nanosatellites to reach the interior electronics. Hitting these electrons may cause differential charging on electronics that is ultimately responsible for internal electrostatic discharge. On the ground, energetic electron beam experiments are conducted on the plastic encapsulated microcircuits samples that reveal electrical charging and discharging on the electronics residing inside the nanosatellites. Conformal-coated electronics show effective charging mitigation due to high energetic electrons.

DOI： 10.2514/1.A33592

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Dielectric temperature spectroscopy of degraded solar cell coverglass due to ground-based space environmental irradiation 査読有り国際誌

Chen Y., Chen L., Toyoda K., Cho M., Cheng Y.

Astrophysics and Space Science Proceedings 47 113 - 122 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© Springer International Publishing AG 2017. Coverglasses are used to protect solar cells from damages caused by space environment irradiation. Damage to coverglasses from space irradiation, the electrostatic discharge and even the breakdown related to surface charging of coverglass are among the main reasons for malfunctioning of solar cells in space missions. This paper using dielectric temperature spectroscopy investigated the typical solar cell coverglasses that were exposed in ground-based simulators to space environments, such as thermal cycling, proton-beam irradiation, electronbeam irradiation, ultraviolet irradiation and their synergistic irradiation. The dielectric properties of coverglasses were measured using a broadband dielectric spectrometer with the frequency range from 0.1 Hz to 1 MHz at temperatures ranging from -140 to 120 ˚ C. It was found that the dielectric constants of five kinds of irradiated coverglasses increase to different degrees at different temperatures compared with the virgin coverglass. And irradiation has little effect on the dielectric loss, DC conductivity and DC conductivity activation energy of coverglasses.

DOI： 10.1007/978-3-319-19309-0_12

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Photoelectron current measurement in low earth orbit using a lean satellite, horyu-iv 査読有り国際誌

Ewang E., Miyahara A., Khan A., Toyoda K., Cho M.

International Review of Aerospace Engineering 10 ( 3 ) 140 - 153 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 Praise Worthy Prize S.r.l.-All rights reserved. This study presents the development and implementation of a photoelectron current measurement system on-board HORYU-IV satellite to take on-orbit measurements from conductive and insulator surfaces. The measurement system aims at providing critical information on photoelectron yield of materials widely used onboard spacecraft. HORYU-IV is the fourth satellites of the HORYU series developed at Kyushu Institute of Technology and it was piggy-back launched on-board H-IIA F30 rocket at an altitude of 575 km on February 17, 2016 (JST). The measurement system mainly consists of current-voltage amplifier circuits for AU, Kapton ® and black Kapton ® samples with gains of 1x, 3x and 1x amplification, respectively. In this article, the analysis of the on-orbit results is presented. The on-orbit results show that a photoelectron current of 2.9nA and 3.1nA was measured from black Kapton® sample at respective elevations of 70.7° and 71.1°. These results respectively correspond to a current density of 14.0μA/m 2 and 18.0μA/m 2 at 71.1°. This study also presents various ground-based tests results performed to verify and validate the effectiveness of the photoelectron current measurement system developed for space applications.

DOI： 10.15866/irease.v10i3.12394

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Microwave Breast Phantom Measurement System with Compact Side Slotted Directional Antenna 査読有り国際誌

Islam M., Mahmud M., Misran N., Takada J., Cho M.

IEEE Access 5 5321 - 5330 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2013 IEEE. In this paper, a new, complete, and comprehensive breast phantom measurement system is presented. A side slotted vivaldi antenna is used for breast phantom measurement. The radiating fins are modified by etching six side slots to enhance the electrical length and produce stronger directive radiation with higher gain. This approach reduces the lower operating frequency and increases the gain and efficiency without compromising the size of the antenna. The overall size of the antenna is 8.8 ( {L} ) ×7.5 ( {W} ) cm {{ {2}}} or approximately 0.4λ × 0.5λ at the first resonant frequency of 1.79 GHz. The results show that the antenna has a fractional bandwidth of approximately 127% from 1.54 to 7 GHz for return loss less than 10 dB with a directional radiation pattern. The average gain of the proposed prototype is 8.5 dBi, and the radiation efficiency is approximately 92% on average over the operating bandwidth. The fidelity factor for face to face is 0.98, and that for side by side is 0.4479, which proves the directionality and lower distortion of the signal. The prototype is successfully simulated, fabricated, and analyzed. The radiating fins of the proposed prototype are optimized to achieve the desired properties for breast phantom measurement. The antenna is used as the transceiver in a breast phantom measurement system to detect unwanted tumor cells inside the breast. An automated electromechanical imaging system with the necessary data post processing makes it an easy and suitable tool for microwave imaging to detect breast tumors.

DOI： 10.1109/ACCESS.2017.2690671

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EM absorption reduction in wireless mobile antenna using printed paper-based metamaterial 査読有り国際誌

Alam T., Islam M., Kibria S., Cho M., Faruque M.

Applied Physics A: Materials Science and Processing 123 ( 1 ) 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2016, Springer-Verlag Berlin Heidelberg. This paper presents a printed negative index metamaterial for electromagnetic (EM) absorption reduction in portable wireless antenna. The perceptible novelty exhibited in this paper is that EM absorption reduction toward the human head with paper-based metamaterial attachment. This research has been performed using human head phantom integrated in the commercially available CST Microwave Studio software package. The EM absorption has been reduced by 13.2 and 6% at 900 and 1800 MHz, respectively.

DOI： 10.1007/s00339-016-0631-5

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Five-year results of the world's first graduate-school-level space engineering fellowship program conducted between the UN and a university - called the PNST program 査読有り国際誌

Maeda G., Cho M.

Proceedings of the International Astronautical Congress, IAC 17 11169 - 11173 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2018 International Astronautical Federation IAF. All rights reserved. September 2017 will mark a major milestone in the “Post-graduate study on Nano-Satellite Technologies (PNST)” fellowship program conducted jointly by the United Nations and Kyushu Institute of Technology (Kyutech) in Japan. In September, the final batch of PNST fellows - four Phd-seeking students and two master-degree-seeking students - arrive at the Tobata Campus of Kyutech to begin their studies of nano-satellite technologies with a strong emphasis on “hands-on” training - using state-of-the-art spacecraft test facilities. They become part of Kyutech's ongoing Space Engineering International Course (SEIC), which is the only English-based, graduate-level, space engineering program in Japan. There are over fifty international and Japanese students enrolled in SEIC. Since the start of the PNST program in 2013, twenty-seven international students have enrolled in it at Kyutech. To date, under PNST, seven students have obtained doctoral degrees and four students have obtained master degrees. In this paper, we explain how outstanding engineering fellows are selected from scores of non-space-faring nations - a pool of tens of millions of young persons. We explain what we set out to do with this UN-academia collaboration in space engineering, and what we have achieved with it.

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Changing the paradigm of developing countries space program: Lean satellite project as a pragmatic option 査読有り国際誌

Tejumola T., Maeda G., Cho M.

Proceedings of the International Astronautical Congress, IAC 9 5707 - 5712 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2017 by the International Astronautical Federation. All rights reserved. Several developing countries have made maiden steps in the establishment of space programs through some forms of cross boarder collaborative satellite development projects, launch and operations efforts. In many of these cases such effort cannot be sustained due to several constraints. New entrants from developing countries with little or no expertise in space technology have been able to access space by exploring the benefits of the explosive growth in satellite industry through the use of small satellites launched with more innovative applications. Several of the new entrants in space industry are filling several technological need gaps by employing the concept of untraditional risk taking approach to achieve low satellite mission cost and fast delivery, i.e., lean satellite. Sustaining space program effort can only be achieved by institutionalizing space program through cost effective strategic road map for human capacity development and establishment of localized space policy. This paper shall peruse the present situation of space technology in developing countries and why these strategies are not sustainable and enumerates the lean satellite project concept as a long-term sustainable space technology development concept for developing countries especially citing several case studies of such projects.

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Establishing space activities in non-space faring nations: An example of university-based strategic planning 査読有り国際誌

Faure P., Cho M., Maeda G.

Proceedings of the International Astronautical Congress, IAC 17 11256 - 11261 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2018 International Astronautical Federation IAF. All rights reserved. In 2015, Kyushu Institute of Technology initiated the Joint Global Multi-Nation Birds Satellite (BIRDS) project. This project has two main goals. First, non-Master or PhD degree holder young professionals from non-space faring nations participate to the design, development, testing, and operation of a 1U CubeSat, whose development costs are secured by the young professional's home institution. Second, the young professionals of BIRDS shall return to their home country and help establishing indigenous space activities. As of September 2017, young professionals from Bangladesh, Ghana, Nigeria, Thailand, Mongolia, Philippines, Malaysia, and Bhutan are being involved in BIRDS project. To help the young professionals acquiring the right tools and preparing them to successfully achieve the second goal of establishing indigenous space activities, the space strategic planning project was established in February 2017. During the project, young professionals from Bangladesh, Ghana, Mongolia, and Bhutan were invited to think about the strategy their home country should be following in the next ten years in order to achieve their country's goals in terms of space sciences, engineering, and utilization, while respecting the country needs and constraints. In this paper, the efforts undertaken by the different young professionals are reported and the guidelines for each country space strategic planning are described. From this work, the authors aim at promoting space activities development in non-space faring nations and encouraging non-space faring nations to find their right strategy to achieve sustainable indigenous space activities despite the nation's constraints.

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Toward Lean Satellites Reliability Improvement Using HORYU-IV Project as Ccase Study 査読有り国際誌

趙孟佑

Acta Astronautica 133 33 - 49 2017年01月

IAC-17.B4.9-GTS.5.3: BIRDS project: Development and operation summery of a cubesat constellation project 査読有り国際誌

Monowar M., Cho M.

Proceedings of the International Astronautical Congress, IAC 10 6405 - 6411 2017年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The growth of CubeSats over the years has created a gateway for developing countries to venture into the development and more need driven satellite technology development. The BIRDS Project is a constellation of 5 CubeSats belonging to 5 countries and to be operated from 7 distributed ground stations all over the world. 15 students from Japan, Ghana, Mongolia, Nigeria, Bangladesh and Thailand developed these satellites at the Kyushu Institute of Technology in Japan applying innovative system Engineering methodology. The 5 identical 1U CubeSats shall execute 6 missions viz; capture homeland picture of participating countries, broadcast voice data from space to ham receivers, detection of Single Event Latch-up (SEL) in space, however because of the gravimetric and volumetric constraints of 1U CubeSat, the three other missions are: determination of precise location of satellite, atmospheric density measurement and demonstration of coordinated ground station network for CubeSats operation planned to be achieved using advantage of 7 distributed ground stations. It is a unique experience for a university to develop five identical CubeSats within a short time, 16 months. The lessons will be shared among the community and applied in future constellation system development. Presently, the satellite development is completed and awaiting launch and deployment from the International Space Station in spring 2017. This paper shall enumerate the system engineering aspect of the development of the satellites and initial operational results after the deployment.

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Screening of nanosatellite microprocessors using californium single-event latch-up test results 査読有り

Tomioka T., Okumura Y., Masui H., Takamiya K., Cho M.

Acta Astronautica 126 334 - 341 2016年09月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2016 IAA. A single-event latch-up (SEL) test using a 252 Cf radioisotope was carried out. The results were compared with those of a proton test and from observation in orbit. A radioisotope can reproduce phenomena observed in orbit that are caused by protons. Considering the inexpensive nature of the 252 Cf test, it is more suitable for nanosatellites that require low cost and fast delivery. A SEL occurrence rate of a commercial-off-the-shelf microprocessor was derived from the ground test results. The 252 Cf test provided a SEL rate approximately 1×10 6 times greater than that in orbit. This data can be used to derive the minimum SEL occurrence rate in orbit and help satellite designers to evaluate the risk of SEL and take measures if necessary.

DOI： 10.1016/j.actaastro.2016.05.004

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A university-based model for space-related capacity building in emerging countries 査読有り

Polansky J., Cho M.

Space Policy 36 19 - 23 2016年05月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2016 Elsevier Ltd. Since 2011 the number of satellites less than 50 kg launched annually has increased by an order of magnitude. This trend is driven in part by proliferation of small satellite and lean satellite projects worldwide. In this decade alone, over 30 new countries are expected to achieve their first satellite in space. More than ever before, emerging countries are engaging in space-related activities. However, barriers such as lack of funding and underdeveloped human resources prevent many emerging nations from initiating or sustaining space programs. Kyushu Institute of Technology (Kyutech) has played an active role in space-related capacity building and international cooperation since 2009, then partnering with the United Nations Office for Outer Space Affairs to formulate a long-term fellowship programme hosted at Kyutech. Growing out of the success of the fellowship programme, Kyutech began significantly expanding its space-related capacity building project in 2013. This paper gives an overview of Kyutech's university-based model to enhance space-related capacity building and human resource development in emerging countries worldwide, and discusses advantages and disadvantages of alternative approaches.

DOI： 10.1016/j.spacepol.2016.01.001

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Toward the improvement of lean satellites reliability through testing - The HORYU-IV (aegis) nano-satellite case study 査読有り

Faure P., Tanaka A., Cho M.

Proceedings of the International Astronautical Congress, IAC 2016年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2016 by Pauline Faure and Mengu Cho, Kyushu Institute of Technology. All rights reserved. What comes to your mind when small satellites are mentioned? For a part of the space community, they represent the possibility of building a satellite despite lack of resources; and hope, through successful achievement, to be recognized as a positive contributor to space science, technology, and engineering. For another part, small satellites represent the black sheep of satellites engineering in the sense that they have the highest rate of infant mortality and mission failure, and a non-functional satellite is another space debris. High rate of infant mortality and mission failure of small satellites tend to point out that ground based testing is not carried out optimally or sufficiently. Moreover, small satellites, especially micro-to pico-satellite are relatively new comers on the space scene and documentation on their development philosophy, testing strategy, and on-orbit operations is scarce. Currently, work to define an adapted testing strategy for small satellites is undergoing through the ISO on "Design Qualification and Acceptance Tests of Small Spacecraft and Units" (ISO/CD 19683). Based on this framework, HORYU-IV testing strategy was established. Experimental data show that most failures are discovered during the early stage of testing. Moreover, experimental data show the importance of interfaces verifications. Overall, a failure was detected on average every 20h of testing. HORYU-IV failures taxonomy is also presented. In addition to testing data, simulations were carried out. The plots of the number of detected defects versus time are in good correlation with the testing data. Moreover, impact of failure criticality on overall project schedule and cost was evaluated. Simulations results show that drastically increasing the initial testing time does not drastically increase reliability, but does drastically increase cost by more than 80%. Through this paper and the presented results, the authors intend to serve as a reference and help each lean satellite program developer deciding how much time should be invested in the testing phase based on a trade-off between the desired reliability after launch for a given time and reasonable project development time and cost.

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IAA study on lean satellites 査読有り

Cho M., Graziani F.

Proceedings of the International Astronautical Congress, IAC 2016年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved. In recent years, the explosive growth of small satellites launches raises concern over space debris, safety, radio spectrum use, and so on. Small satellites range from a 1kg CubeSat to a satellite weighing well over 100kg, but have a common characteristic of low-cost and fast-delivery. Nowadays, even commercial CubeSats have started to appear. In 2014, an activity started at ISO/TC20/SC14 to make an ISO standard that defines what is a small satellite and sets requirements for small satellites to answer those concerns and to lay down the foundation for commercial activities utilizing small satellites. Since 2015, a new work item ISO/WD/20991, "Requirements for Small Spacecraft" is being discussed at ISO. Under these circumstances, the study group 4.18, "Definition and Requirements of Small Satellites Seeking Low-Cost and Fast-Delivery", was initiated in 2014. The objectives are to examine the definitions of small satellites, identify the requirements every satellite should follow regardless of its size or development philosophy and then reflect some of the findings to the ISO draft. After a series of meetings, the final draft of the study group report has been submitted to IAA Commission 4 in March 2016. The purpose of the present paper is to provide overview of the study group findings. The definition of small satellite was discussed extensively. The major conclusion of the study group is that mass nor size is not suitable to define small satellites and they should be defined by the philosophy of design, manufacturing, mission, program management and others. The study group came to conclusion that "lean satellite" is the most suitable word to describe a satellite that utilizes untraditional risk-taking development approaches to achieve low-cost and fast-delivery with a small number of team. The smallness is merely the result of the approaches. Scaling to measure how closely a given satellite fits into the concepts of lean satellites in terms of (1) total cost, (2) delivery time, (3) simplicity, (4) risk taking, (5) risk mitigation, (6) reliability requirement, (7) mission duration, (8) launch, and (9) waste minimization has been developed in. The scaling has been tested against nearly 30 satellites all over the world. At the symposium, the contents of the study group final draft will be presented as well as the update of the ISO standards related to lean/small satellites.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85016507297&origin=inward

Development philosophy and flight results of arc event generator and investigation satellite HORYU-IV 査読有り

Cho M., Faure P., Tanaka A.

Proceedings of the International Astronautical Congress, IAC 2016年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright 2016 by Kyushu Institute of Technology. HORYU-IV satellite is the fourth satellite in the HORYU series to be developed at Kyushu Institute of Technology and the second satellite of the series to be piggy-back launched on H-IIA. The first to be launched was HORYU-II in May 2012, which successfully demonstrated the feasibility of generating 350V in low Earth orbit. HORYU series are categorized as lean satellites. A lean satellite is a satellite that utilizes non-traditional, risk-taking development and management approaches - with the aim to provide value of some kind to the customer at low-cost and without taking much time to realize the satellite mission. HORYU series satellites are dedicated to spacecraft charging and high voltage experiments which are not always welcomed as payloads on a shared platform due to concern over disturbance caused by discharge. Lean satellites are ideal testing platforms for those risky experiments. HORYU-IV is a cubic satellite within an envelop of 450mm × 420mm × 430mm and weighs approximately 10kg. Its structure and bus are mainly inherited from HORYU-II with various improvements in functionality and reliability. Especially, many layers of power cycle reset against single event effects were implemented. HORYU-IV implements HORYU-II high voltage photovoltaic power generation technology and uses it to study discharge phenomena. HORYU-IV's main mission is to acquire an arc current waveform by an onboard oscilloscope and capture its image by a camera triggered by the oscilloscope. In addition, HORYU-IV plans to carry out scientific experiments on arc-mitigation high voltage solar array, plasma measurement using a double Langmuir probe, vacuum arc thruster, photoelectron current measurement, and polymer material degradation. HORYU-IV project started in Mary 2013 and the flight model was delivered to JAXA in January 2016. On February 17, 2016, it was successfully launched by a H-IIA rocket to an orbit of 575 km altitude with 31o inclination as a piggyback satellite. The operation strategy was to carry out the main mission as soon as possible after the launch considering the high infant mortality rate of lean satellites. After initial check of the satellite house keeping data, the main mission was executed and the preliminary result indicates the mission was successfully conducted. It is planned to operate the satellite for at least two years in orbit. At the time of symposium, overview of the satellite, especially its development philosophy as a lean satellite, will be given along with some preliminary flight results obtained during the eight months in orbit.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85016511987&origin=inward

Aoba Velox-IV attitude and orbit control system design for a LEO mission applicable to a future lunar mission 査読有り

Cordova-Alarcon J., Örger N., Kim S., Soon L., Cho M.

Proceedings of the International Astronautical Congress, IAC 2016年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved. Aoba VELOX-IV is a 2U-Cubesat which will serve as a platform for technology validation towards a future lunar mission for the observation of lunar horizon glow (LHG). LHG was first spotted in 1966 and 1968 by onboard cameras on Surveyor spacecraft after the sunset from the western horizon, and Apollo astronauts reported that they had seen the horizon glow. Even though the horizon glow was highly visible in the Apollo 15 sunset, Apollo 16 showed no traces of the horizon glow, proving that it is a highly varying phenomenon. Nanyang Technological University (NTU Singapore) is collaborating with Kyushu Institute of Technology (Kyutech), to build Aoba VELOX-IV, which will be launched by Japan's national agency, the Japan Aerospace Exploration Agency (JAXA) in 2018. Though its AOCS scheme is designed to meet the requirements for a low-Earth-orbit (LEO) mission, it can be directly applicable to a lunar mission. This paper is dedicated to the description of the design and analysis of a AOCS to meet these requirements. Because of dimension restrictions, the satellite attitude is two-axis controlled. The hardware of AOCS consists on Sun sensors, gyroscope, reaction wheels and pulsed plasma thrusters (PPT). Satellite position, velocity and time will be determined by a ground station and the satellite will propagate them until the next revisit. Based on PPT thrusters, the AOCS will desaturate RW during attitude control maneuvers for the pointing towards Earth horizon in such a way that the satellite can observe sunrise and sunset. In eclipse phase, the satellite is required to know its attitude by means of Kalman filtering to observe the sunrise. The geometry configuration of PPT will allow the extension of the satellite mission lifetime while desaturation of RW and while the satellite is visible to the ground station.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85016465553&origin=inward

Birds project: An innovative way to educate post-graduate students from developing countries 査読有り

Maeda G., Cho M.

Proceedings of the International Astronautical Congress, IAC 2016年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved. With help of the United Nation's "Post-graduate study on Nano-Satellite Technologies (PNST)", Kyushu Institute of Technology (Kyutech) has an unusually large number of space engineering graduate students from developing countries (currently 33 such students from 19 countries). All PNST fellows and all self-funded overseas students are enrolled in our "Space Engineering International Course (SEIC)", which has a strong emphasis on hands-on training. We believe the best way to master satellite technology is to design, build, launch, and operate, a real satellite, within given time constraints - in Japan the standard duration for a masters degree is two years. We wish to describe one hands-on international project of SEIC, which in October of 2016 will be past the halfway point. The BIRDS Project started in October of 2015 with 15 students - 3 Japanese and 12 from developing countries. None have designed a spacecraft before. They represent five nations, and the goal is for the students of each nation to build a 1U cubesat for their nation - of which four are non-space faring nations. The students hammer out the design themselves, and then each cubesat is built to that common design using commercially available parts. Hence, when in LEO, the five cubesats will form the first constellation of 1U cubesats designed, built, and flown, by university students. Launch (to the ISS) is set for second quarter of 2017. The schedule is exceedingly ambitious. The project has six missions: (1) capture images of their homelands, (2) broadcast songs to ham radio stations of their homelands (using the onboard "Digi Singer" device), (3) determine precise satellite location by examining the time lag of signals received at several ground stations (because there is no room for GPS in BIRDS cubesat), (4) measure atmospheric density based on the aforementioned precise location information, (5) demonstrate the feasibility of a ground station network based on university facilities in developing nations, and (6) investigate single-event latch-up's by carefully assessing onboard resets. When students go through all of the above, it becomes a uniquely intensive and extensive space technology learning experience. Of course, each student is assigned specific roles (e.g., mechanical design of the cubesat frame or design of the camera system). However, in the end, each will have participated in the entire process from design to in-orbit operation.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85016450824&origin=inward

Aoba Velox-IV camera system design for lunar horizon glow imaging in a future lunar mission 査読有り

Örger N., Cordova-Alarcon J., Toyoda K., Soon L., Cho M.

Proceedings of the International Astronautical Congress, IAC 2016年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved. The lunar horizon glow (LHG) was first spotted in 1966 and 1968 by onboard cameras on Surveyor spacecraft after the sunset from the western horizon, and Apollo astronauts reported that they had seen the horizon glow. Surveyor missions observed lunar horizon in different distances, angles and time periods (from 0.5 to 2.5 hours after local sunset). Even though the horizon glow was highly visible in the Apollo 15 sunset, Apollo 16 showed no traces of the horizon glow. Therefore, it is highly varying phenomenon. Aoba VELOX-IV is a technology demonstration 2U CubeSat platform for LHG imaging in a future lunar mission. Nanyang Technological University (NTU Singapore) is collaborating with Kyushu Institute of Technology (Kyutech), to build Aoba VELOX-IV, which will be launched by Japan's national agency, the Japan Aerospace Exploration Agency (JAXA) in 2018. In this paper, the requirements of the LHG imaging system will be presented as well as hardware design, operation modes, sensitivity, power consumption and software. The camera options are limited due to power, volume and mass constraints. In addition, communication constraints for a lunar mission limit these options further. The horizon must be observed from the night side due to the physical mechanism of the LHG, and the visible light range must be selected as focus in order to provide evidence for Apollo observations. Also, this operation may require horizon detection to have a right perspective to capture the forward scattered light of the LHG, which is directly related to attitude determination and control subsystem. AOCS will rotate the camera to observe the horizon during the local sunset or sunrise.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85016479558&origin=inward

Vacuum Arc Thruster Development and Testing for Micro and Nano Satellites

AHEIEVA Kateryna, TOYODA Kazuhiro, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 14 ( 30 ) Pb_91 - Pb_97 2016年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

This paper will describe the development of the Vacuum Arc thruster (VAT) for micro and nano satellites with the main purposes of: attitude control, maintaining orbit-satellite deorbiting. Firstly, this VAT thruster is integrated on-board student microsatellite Horyu-IV, which was developed at the Kyushu Institute of Technology (KIT), Japan. The satellite will be launched in the fiscal year 2015 by H2A rocket. This paper describes the principles of VAT as a direct drive from High Voltage Solar Array (HVSA). Expected performance of this vacuum arc thruster with passive ignition (space plasma condition) was measured. We propose a method for improving the thruster efficiency. Results show that the impulse bit was of the μNs order, and the thrust–56 nN– and efficiency– 2.5%–were calculated. Moreover, it was found that the impulse bit changes with the applied voltage. A new CFRP material was developed and used as a cathode for the purpose of improving efficiency. Discharge characteristics of current and the arc rate are presented. Measurements of impulse bit were also done for the VAT in configuration with two different propellants (commercial and new CFRP) and with a permanent magnet of 300 mT.

DOI： 10.2322/tastj.14.Pb_91

その他リンク： http://ci.nii.ac.jp/naid/130005172062

Finite Element Analysis of Vibration Amplification Distribution in Lean Satellites

BATSUREN Amgalanbat, HATAMURA Toru, MASUI Hirokazu, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 14 ( 30 ) Pf_51 - Pf_60 2016年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

This paper presents a part of the basic research for establishing the unit Qualification Test (QT) conditions within the framework of an international project to make ISO standard, namely, "Space Systems—Design Qualification and Acceptance Tests for Small-Scale Satellites and Units Requiring Low Costs and Fast Delivery". A laboratory test is conducted to study how vibration acceleration is distributed in a satellite body, so as to define the unit QT random vibration test level. The range of natural frequency and the amplification of acceleration are identified through statistical analysis of the test results. Finite element analysis is carried out to extend the findings to other structural types of micro/nanosatellites. Three structural types are analyzed, i.e., Yojo han, T-type and Pi-type. Based on the results, a unit QT vibration level that provides the minimum reliability assurance for use in space is proposed.

DOI： 10.2322/tastj.14.Pf_51

その他リンク： http://ci.nii.ac.jp/naid/130005246080

Development of Low Cost Double Probe Plasma Measurement System for a Lean Satellite HORYU-IV

TEJUMOLA Taiwo R., TANAKA Atomu, KHAN Arifur, HORYU-IV Project Team, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 14 ( 30 ) Pr_39 - Pr_46 2016年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

A lean satellite is equivalent to a small/micro/nano/pico satellite that utilizes untraditional risk-taking development approaches to achieve low-cost and fast-delivery. Lean satellites have demonstrated great ability to be used for the study of space plasma and Earth's ionosphere which has helped in the prediction of many astrophysical phenomena and forecasting of geophysical changes on ground. Several methods have been employed in the measurement of space plasma parameters over the years using the Langmuir Probe. These methods employed different techniques using single probes or double probes. Single probe requires a well-defined reference which is difficult in small spacecraft. Moreover, high current flow in the saturation mode may destroy the probe and on-board circuitry. A low cost double Langmuir probe made of gold with its measurement circuit has been designed and tested inside RF generated Argon plasma in the pressure of 1.4×10-2 Pa that confirms the electron density from 1010 to 1012 m-3. Important design considerations such as operability of the designed system in low earth orbit grade plasma, mitigation of probe contamination and sputtering of the electrode surface were analysed in the paper to ensure that the developed system can provide high fidelity plasma measurement data throughout the life span of HORYU-IV (Arc Event Generator and Investigator Satellite) which is a 13 kg, 40 cm cubic lean satellite under development at the Kyushu Institute of Technology.

DOI： 10.2322/tastj.14.Pr_39

その他リンク： http://ci.nii.ac.jp/naid/130005172210

Design and Testing of Electrical Power Subsystem of a Lean Satellite, HORYU-IV

EDRIES Mohamed Yahia, TANAKA Atomu, HORYU-IV Team, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 14 ( 30 ) Pf_7 - Pf_16 2016年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

HORYU-IV is a lean satellite weighing 10 kg or less designed at the Kyushu Institute of Technology. It is planned to be launched with the ASTRO-H in FY2015 as a piggyback on an H-IIA rocket. The main mission of HORYU-IV is to acquire on-orbit data of discharge phenomena occurring on high-voltage solar arrays. An electrical power subsystem (EPS) is one of the HORYU-IV bus subsystems. The function of the EPS is to provide uninterrupted power to all subsystems during the satellites lifetime. High reliability, high efficiency and simplicity are the main requirements to be considered in the design of an EPS. Generally, an EPS consists of solar arrays, rechargeable batteries, and a power control and distribution unit (PCDU). A peak power tracking topology is preferred to extract the maximum power generated by the solar arrays. The extra energy is stored in nickel-metal hydride batteries. The simple design and usage of available commercial-off-the-shelf components are the main features of the PCDU which controls the battery charging and load voltage regulation. Functional tests under different operating conditions were carried out on the designed EPS to qualify its performance. The aim of this paper is to explain the design of the EPS, and to present and analyze the test results.

DOI： 10.2322/tastj.14.Pf_7

その他リンク： http://ci.nii.ac.jp/naid/130005126067

Classification of Countries Worldwide according to Satellite Activity Level

POLANSKY John, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 14 ( 30 ) Pv_7 - Pv_16 2016年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Emerging countries worldwide can benefit technologically, economically, and socially from domestic space-related activities. However, limited resources and lack of know-how prevent many non-space faring nations from initiating space projects, much less building sustainable space or satellite programs. New opportunities exist to overcome these barriers. The number of small satellites launched in the last three years has increased by an order of magnitude, and the market of satellites less than 50kg is projected to grow from $700M USD in 2014 to $2B USD by 2019. This paper gives an overview of space-related activities in various emerging countries and categorizes countries in nine regions worldwide according to level of satellite activity.

DOI： 10.2322/tastj.14.Pv_7

その他リンク： http://ci.nii.ac.jp/naid/130005331244

超小型衛星「鳳龍弐号」の熱設計・検証手法と軌道データ解析

増井博一, 世利祐樹, 濱田朗充, 趙孟佑

日本航空宇宙学会論文集 64 ( 5 ) 270 - 275 2016年01月

記述言語：日本語掲載種別：研究論文（学術雑誌）

This paper describes the thermal design method of Horyu-2. Horyu-2 was developed by Kyushu Institute of Technology. The project started in 2010 and Horyu-2 was launched by H-2A of JAXA on May 18 2012. At present, Horyu-2 is carrying out many missions and transferring on-orbit data. Horyu-2 orbits 680 km with sun-synchronous polar orbit. Feature of Horyu-2 are lightweight (7.1kg) and large surface (30cm cube) compared with a conventional cube-sat. Thermal design is needed to keep the temperature within the safe range. We conducted thermal analysis in a step-by-step in each phase. This paper reviews the thermal design processes and discusses on-orbit data acquired after launch.

DOI： 10.2322/jjsass.64.270

その他リンク： http://ci.nii.ac.jp/naid/130005249170

5. おわりに(宇宙機と宇宙プラズマ相互作用による放電現象の地上実験と軌道上実験)

増井博一, 趙孟佑

プラズマ・核融合学会誌 91 ( 11 ) 738 - 739 2015年11月

記述言語：日本語掲載種別：研究論文（学術雑誌）

本講座では宇宙機で発生する放電現象についてこれまで述べた.宇宙工学の分野の中でも非常に狭い領域のトピックを取り扱った.しかし,宇宙機の電源システムに直接影響を与える,非常に重要な分野であることは理解頂けたと思う.以下に本講座の総括と今後の展望を述べる.

その他リンク： http://ci.nii.ac.jp/naid/110010016774

宇宙機と宇宙プラズマ相互作用による放電現象の地上実験と軌道上実験(4)放電現象解明のための軌道実証結果の紹介(3)超小型衛星による高電圧発電の実証(鳳龍弐号)

増井博一, 趙孟佑

プラズマ・核融合学会誌 91 ( 11 ) 735 - 737 2015年11月

記述言語：日本語掲載種別：研究論文（学術雑誌）

宇宙空間での高電圧の発電を実証するために開発された「鳳龍弐号」での実験結果を紹介する.鳳龍弐号では太陽電池を使用しての300V以上の発電電圧の実証と放電実験が行われた.この発電電圧は現在の所,宇宙空間で太陽電池が作りだした電圧としては最も高い値である.このような挑戦的な実験が可能となったのは,大学を中心として超小型衛星が盛んに開発されており,宇宙空間を使用しての実験は以前に比べ格段に敷居が下がった為である.超小型衛星を使用することでリスクの高い軌道上実証が可能となり,鳳龍弐号のような高電圧を使用する実験も可能となった.ここでは「鳳龍弐号」の開発や軌道上実験の結果と今後の展開について概説する.

その他リンク： http://ci.nii.ac.jp/naid/110010016773

宇宙機と宇宙プラズマ相互作用による放電現象の地上実験と軌道上実験(2)宇宙機での放電現象

趙孟佑, 増井博一

プラズマ・核融合学会誌 91 ( 9 ) 614 - 618 2015年09月

記述言語：日本語掲載種別：研究論文（学術雑誌）

この講座では,宇宙機で発生する放電現象を紹介する.第2章では宇宙機で発生する放電のメカニズムについて紹介し,この放電を抑制する事が次世代宇宙機の高電圧化に欠かせない技術である事を説明する.第3章では,地上で行われる宇宙機の放電に関わる実験について紹介する.また,この数年で行われた軌道上実証実験の結果について第4章で説明を行う.

その他リンク： http://ci.nii.ac.jp/naid/110010016667

超小型衛星の衝撃試験レベル調整方法に関するシミュレーション査読有り

畑村透、増井博一、趙孟佑、前野一夫

日本航空宇宙学会論文集 2015年06月

A compact circularly polarized high gain S‐band nanosatellite antenna using ramped convergence particle swarm optimization (共著) 査読有り

M. Samsuzzaman, M. T. Islam, S. Kibria, and M. Cho

Microwave and Optical Technology Letters 57 1503 - 1508 2015年06月

Compact Antenna for Small Satellite Applications (共著) 査読有り

M. T. Islam, Mengu Cho, M. Samsuzzaman, and S. Kibria

IEEE Antennas and Propagation Magazine 57 ( 2 ) 30 - 36 2015年04月

Effects of Space Environmental Exposure on Photoemission Yield of Polyimide 査読有り

J. Wu, A. Miyahara, A. R. Khan, M. Iwata, K. Toyoda, M. Cho, X. Q. Zheng

IEEE Transactions on Dielectrics and Electrical Insulation 22 ( 2 ) 1204 - 1212 2015年04月

Flight Experiment Results of Electron-Emitting Film for Spacecraft Charging Mitigation 査読有り

Naoki Matsumoto, Atomu Tanaka, Arifur R Khan, Minoru Iwata, Kazuhiro Toyoda and Mengu Cho

Journal of Spacecraft and Rockets 52 553 - 559 2015年03月

Flight Results of Arcing Experiment Onboard High-Voltage Technology Demonstration Satellite HORYU-II 査読有り

Shunsuke Iwai, Hirokazu Masui, Minoru Iwata, Kazuhiro Toyoda and Mengu Cho

Journal of Spacecraft and Rockets 52 544 - 552 2015年03月

Reliability growth of a nano-satellite through assembly, integration and testing 査読有り

Cho M., Faure P.

Proceedings of the International Astronautical Congress, IAC 11 8652 - 8660 2015年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

There is an increasing demand for nano-satellite development worldwide. Its advantages are low-cost and fast-delivery. Its success rate is, however, much lower than traditional satellites. The satellite reliability can be modelled by Weibull statistics. A satellite goes through a series of assembly, integration and testing (AIT) activities. The activities may detect various defects in design, material, workmanship, etc. Once a defect is detected, it is corrected and the AIT resumes or the development process goes back to an earlier phase. The failure rate keeps decreasing as the AIT continues until it becomes a steady value indicating the shift to the random failure mode. The present paper demonstrates how the reliability is improved through AIT activities based on the real data taken during the AIT campaign of a nano-satellite. The reliability growth curve is drawn by plotting the cumulative number of defects found during the testing against the total testing time or testing items. Monte Carlo Simulation was also carried out to simulate the stochastic process where a defect is detected by each AIT activity. The overall AIT time is calculated and compared to the final reliability that depends on how many of latent defect remain undetected.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84991510670&origin=inward

University partnerships as a model for capability building in emerging space nations 査読有り

Wood D., Polansky J., Cho M.

Proceedings of the International Astronautical Congress, IAC 6 4260 - 4282 2015年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Organizations within many developing countries arc identifying space and smaD satellite technology as priority areas in which to increase their local capability. Satellites provide valuable public services in the areas of earth observation, communication, positioning, timing and scientific research. Small satellite projects arc also an opportunity for universities and government agencies to foster goals in educating students, stimulating innovation, enhancing the capability of local firms, pursuing strategic international alliances and fostering national pride. As a nation that is new to space begins early activities small satellites, it is valuable to develop partnerships with more experienced space nations that can provide mentorship. Such partnerships come in a variety of models, including political agreements between governments, commercial contracts with firms and educational agreements with universities. Each of these models has benefits and weaknesses; each may be appropriate for ait emerging space nation depending on their local context, objectives and stakeholder needs. This paper considers the opportunities and challenges facing developing nations that harness international university collaborations with more experienced space nations as part of their strategy to increase local capability in small satellites. Specifically, the paper presents examples of university programs led by the Kyushu Institute of Technology, which is serving as a mentoring partner to many developing countries that are starting new small satellite programs. The university partnership model is particularly appropriate for a nation that seeks a long term process of capability building that fosters education and the maturation of new space-related agencies, firms or university programs. The Space Engineering International Course of the Kyushu Institute of Technology is an example of a program offered by a mentor nation that supports such goals. This paper describes the educational and technical components of the Space Engineering International Course (SEIC). The discussion provides several examples of experiences within the SHC program. The SEIC exposes students to academic education, hands-on satellite programs, international teams and professional development opportunities. The paper provides advice to leaders of universities and space related agencies in less experienced space nations as they consider how to best take advantage of international university collaborations. At the same time, the paper addresses university leaders in more experienced space nations, highlighting models and techniques that will help them build mutuaDy beneficial and sustainable relationships as a mentoring partner.

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IAC-15-B4.7.3 IAA Study on lean satellites definition and requirements 査読有り

Cho M., Graziani F.

Proceedings of the International Astronautical Congress, IAC 6 4745 - 4750 2015年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

There is increasing demand of small satellite development and utilization worldwide. The recent explosive growth of the small satellite launch has caused significant concerns among traditional space sector. Peaceful coexistence of the traditional sector and the emerging sector is crucial. There is a need to define "what is a small satellite" and lay out the requirements of small satellites. In 2014, an activity started to make an ISO standard to describe definition and requirements of small satellites. In parallel, a new study group was initiated at International Academy of Astronautics. The study group intends to make an important input to the ISO standard. Definition of small satellite was discussed extensively in the study group. The majority of the opinions were that mass nor size is not suitable for definition of small satellites and they should be defined by the philosophy of design, manufacturing, mission, program management and others. The workshop came to conclusion that "lean satellite" is the most suitable word to describe a satellite that utilizes untraditional risk-Taking development approaches to achieve low-cost and fast-delivery with a small number of team. This paper provides the recent update on the lean satellite standard.

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Development of mission payloads for arc event generator and investigation satellite HORYU-IV 査読有り

Fukuda H., Shimizu T., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 12 9766 - 9771 2015年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2015 by the International Astronautical Federation. A nano-satellite "HORYU-4" is under development in Kyushu Institute of Technology (Kyutech) and is planed to be launched in FY 2015. The main mission of HORYU-4 is measurement of discharge phenomenon (e.g. discharge current, discharge point) on orbit. The one of the submission of this satellite is demonstrate of discharge mitigation method. The discharge experiment system is needed for this mission. This paper introduces the over view of HORYU-4, and discusses following contents: 1, Development of EM of the discharge experiment system. 2, Ground-based discharge tests at Kyutech. This mission will be first measurement of arcing current in space orbit. It will be able to evaluate the validity of ground-based test systems by comparing the result of ground-based tests with experiments conducted in space.

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Development of S band antenna for Nanosatellite 査読有り

Islam M., Samsuzzaman M., Kibria S., Cho M.

2014 IEEE Asia-Pacific Conference on Applied Electromagnetics, APACE 2014 - Proceeding 16 - 19 2015年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2014 IEEE. In this paper, a circularly polarized, high gain, patch antenna with low axial ratio dedicated for S band nanosatellite communications is presented. Four asymmetric V-shaped slits in the diagonal directions on the square patches and a parasitic element are introduced to create circularly polarized (CP) radiation with a large axial ratio beamwidth. A prototype of the antenna was developed with a 1.57 mm thick single layer Rogers's substrate with a relative permittivity of 2.2. Simulation and measurement results are given, indicating that this S band antenna realizes the required HORYU-IV nanosatellite specifications in terms of frequency bandwidth, gain, circular polarization bandwidth, and axial ratio (AR) beamwidth.

DOI： 10.1109/APACE.2014.7043768

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Deorbit system based on vacuum ARC thruster for microsatellite 査読有り

Aheieva K., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 4 2644 - 2648 2015年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In this article presented Vacuum Arc Thruster (VAT), which was designed and manufactured in Kyushu Institute of Technology. Presented principle of work and design. Thruster, firstly, will be operating onboard satellite Horyu-4, which will be launch in 2015 and demonstrate work with direct power source-High Voltage Solar Array (300 V). For VAT presented main discharge and power characteristics measured in experiments. Was calculated thrust (56 nN) and efficiency (2.5 %). Specific impulse is 1200 sec, impulse bit 2 uNs. The total weight of the system including circuit and mounts to satellite is 32 grams. Presented results for efficiency improving methods, such as new type of propellant use in the thruster and magnet system. Calculated deorbit time dependence to satellite mass and power consumption for Vacuum Arc Thruster.

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Status QUO and future perspectives of UNISEC-global 査読有り

Kawashima R., Cho M.

Proceedings of the International Astronautical Congress, IAC 13 10412 - 10413 2015年01月

Special issue on spacecraft charging technology

Garrett H., Whittlesey A., Ferguson D., Minow J., Bodeau M., Davis V., Parker L., Wheelock A., Roussel J., Payan D., Hilgers A., Rodgers D., Cho M.

IEEE Transactions on Plasma Science ( IEEE Transactions on Plasma Science ) 42 ( 9 ) 2014年09月

Influence of atomic oxygen exposure on surface resistivity of silicon doped polyimide affecting spacecraft charging（共著）査読有り

Noor Danish Ahrar Mundari, A.K. Srivastava, Kazuhiro Toyoda, Mengu Cho

Vacuum 105 11 - 16 2014年07月

350-V Photovoltaic Power Generation in Low Earth Orbit（共著）査読有り

Mengu Cho, Hirokazu Masui, Shunsuke Iwai, Tatsuya Yoke, Kazuhiro Toyoda

Journal of Spacecraft and Rockets 51 379 - 381 2014年05月

Characterization Experiments of Secondary Arcs on Solar Arrays: Secondary Arc Physical Parameters（共著）査読有り

Hirokazu Masui, Takayuki Ose, Tomoki Kitamura, Kazuhiro Toyoda, Mengu Cho

Journal of Spacecraft and Rockets 51 ( 3 ) 922 - 930 2014年05月

Thermal Vacuum Test Results for Virtex-5 FPGA Based Multi-core On-Board Computer（共著）査読有り

Mohamed Mahmoud Ibrahim, Kenichi Asami, Mengu Cho

IEEE AeroSpace 2014 2014年03月

Effects of Ultraviolet Irradiation and Atomic Oxygen Erosion on Total Electron Emission Yield of Polyimide（共著）査読有り

J. Wu, A. Miyahara, A. R. Khan, M. Iwata, K. Toyoda, M. Cho, X. Q. Zheng

IEEE Transactions on Plasma Science 42 ( 1 ) 191 - 198 2014年02月

Charging and Arcing Test on Semi-conductive Coated Solar Coupon Panel（共著）査読有り

Akitoshi Takahashi, Minoru Iwata, Ryo Muraguchi, Mengu Cho

IEEE Transactions on Plasma Science 42 ( ２ ) 384 - 390 2014年02月

Space education and outreach using a digi-singer on-board a nano-satellite 査読有り

Nakano T., Shimizu T., Chen D., Almubarak H., Cho M.

Proceedings of the International Astronautical Congress, IAC 12 8510 - 8513 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright 2014 by Ms. Tae Nakano. Published by the IAF. Currently, there is no education curriculum that teaches space development or utilisation in Japanese elementary or junior high schools. The early education is vital for such young students to get an interest for future carrier. The aim of this project is to provide an opportunity to understand space related industries. The Kyushu Institute of Technology (Kyutech) has conducted an educational program for students in elementary and junior high schools in collaboration with a local science museum with support from the Japanese Ministry of Education since 2009. In this program, the children experience a part of satellite development together with university students and receive Morse beacon sent from the nano-satellite HORYU-II using a handy receiver and a handmade Yagi antenna. Such signal can be easily acquired without special equipment, but requires special training or a computer program to decode the signal, and hence this is not so appealing to the children. HORYU-IV is a high voltage experiment nano-satellite (30cm cubic, < 10kg mass) under development at Kyutech and to be launched in FY2015. HORYU-IV payload includes Yamaha's eVOCALOID (TM) LSI as an on-board vocal synthesiser, namely digi-singer. Thanks to it, children could experience space not only in science classes, but also in classes of music, art, or physical education. Audio from the digi-singer is not only used for school education, but also for events and creative activities such as a dancing event and illustration, and can attract people who have no special interest in space technologies.

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Selection of commercial-off-the-shelf antistatic coating and its applicability for space-use solar arrays 査読有り

Iwata M., Takahashi A., Sakamoto M., Cho M., Muraguchi R.

Transactions of the Japan Society for Aeronautical and Space Sciences 57 ( 3 ) 153 - 159 2014年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

In recent years, the power generation requirement of spacecrafts has increased in order to load them with many mission devices and to extend their lifetime, hence, high voltages are used. However, such high voltages can cause electrostatic discharges on solar arrays, resulting in damage to the solar arrays. Therefore, we use an antistatic coating, which mitigates the surface charging on solar cells, in order to prevent the discharge. It is considered that an antistatic coating can mitigate surface charging and can prevent discharges on solar cells. The purpose of this research is to develop a coating to mitigate the surface charging applicable to geostationary Earth orbit satellites. We selected a candidate coating with the required surface resistivity and vacuum resistance. Furthermore, we selected a commercial-off-the-shelf antistatic coating after considering the experimental results of charging mitigation performance when simulating the charging condition in space. The candidate agent was coated on a conventional solar array coupon panel, and the charging mitigation performance of the latter was evaluated. We have confirmed a dramatic improvement in charging mitigation performance with this coated conventional solar array coupon. © 2014 The Japan Society for Aeronautical and Space Sciences.

DOI： 10.2322/tjsass.57.153

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Role of aging on the threshold of electrostatic discharge on solar array coverglass 査読有り

Khan A., Hughes R., Chen Y., Toyoda K., Cho M., Gray A.

Proceedings of the International Astronautical Congress, IAC 11 8036 - 8040 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2014 by the International Astronautical Federation. All rights reserved. Coverglass has been widely used to cover the solar cells of satellite solar arrays. This acts to protect the arrays from damage due to irradiation by UV, protons, electrons, etc. However, charge accumulation due to high-energy proton/electron irradiation or ageing due to thermal cycling may degrade the quality and affect the threshold for electrostatic discharge (ESD) from the coverglass. In order to reveal the effect of aging on the threshold for ESD in an inverted potential gradient (IPG) condition, several coverglass samples (CMG100-AR) produced by Qioptiq Ltd. have been aged by thermal cycling (-160 to +110 C) and high-energy (500 keV) electron beam irradiation. A ground experiment was conducted by placing virgin and exposed (aged) samples in vacuum, irradiating the samples with a beam of energetic electrons to generate an artificial ESD, and measuring the sample's surface potential by a non-contact method before and after the discharge occurred. Statistical analysis and Weibull distribution confirms that the ESD threshold for aged coverglass is higher than that of virgin.

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Three hundred fifty volt photovoltaic power generation in low Earth orbit 査読有り

Cho M., Masui H., Iwai S., Yoke T., Toyoda K.

Journal of Spacecraft and Rockets 51 ( 1 ) 379 - 381 2014年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

A nanosatellite, HORYU-II, weighing only 7.1 kg achieved the highest photovoltaic power generation in orbit, at 350V, breaking the previous record from the International Space Station, at 160 V, by more than a factor of two. The satellite uses a permanent magnet and hysteresis dumper to do passive attitude control using the Earth's magnetic field. Using series-connected micro solar cells, the satellite can carry out high-voltage experiments in space. The high-voltage solar array developed for HORYU-II is suitable for other scientific experiments that make use of high voltages, such as electric propulsion, spacecraft charging onboard a micro/nanosatellite. It is free from the electromagnetic noise associated with high-voltage dc/dc converters and robust enough to operate for a short time in orbit.

DOI： 10.2514/1.A32559

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Nano-satellite project-based learning for capacity building in basic space technology development 査読有り

Polansky J., Cho M., Balogh W.

Proceedings of the International Astronautical Congress, IAC 12 8398 - 8402 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright ©2014 by the International Astronautical Federation. All rights reserved. In April 2013, Kyushu Institute of Technology (Kyutech) launched a new English-based post-graduate curriculum, the Space Engineering International Course (SEIC). The curriculum is either two years (Masters) or three years (Doctor), and consists of research leading to a Master or Doctor degree, lectures on space engineering, project-based learning (PBL), and on-the-job training in space environment testing. SEIC is open to any student, Japanese or non-Japanese, who registers as a full-time graduate student at the Graduate School of Engineering. PNST (Post-graduate study on Nano-Satellite Technologies) fellows are supported through a United Nations/Japan long-term fellowship programme and comprise the core constituency of non-Japanese students. The PNST fellows are primarily from non-space faring nations and are expected to contribute to indigenous capacity building by bringing the basic space technology development knowledge and skills acquired through their studies at Kyutech back to their home countries or home institutions. The objective of PBL is to perform real-world problem solving to an open-ended question or challenge, for example, nano-satellite mission design that benefits society or developing countries. In this process students learn to apply their technical prowess to a real-world project, enhance systems engineering skills, learn to think as global engineers, and practice inter-cultural communication. Nano-satellite PBL in combination with the other aspects of SEIC is designed to allow students to implement applications-oriented space technology outside of Kyutech upon graduation. This paper details the first year of SEIC and nano-satellite activities at Kyutech, and gives updates of the United Nations/Japan PNST long-term fellowship programme.

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Monte Carlo simulation of reliability growth of small-scale satellites through testing 査読有り

Cho M.

Proceedings of the International Astronautical Congress, IAC 9 6762 - 6771 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2014 by the International Astronautical Federation. All rights reserved. There is an increasing demand of small-scale satellite (a micro/nano/pico satellite seeking low-cost and fast- delivery) development worldwide. The advantages of small-scale satellite are low-cost and fast-delivery. But, currently the success rate of small-scale satellite is much lower than traditional satellites. The satellite reliability can be modelled by Weibull statistics. A satellite system goes through a series of tests. The tests may detect various defects in design, material, workmanship, etc. Once a defect is detected, it is corrected and the test resumes or the development process goes back to an earlier phase. The failure rate decreases due to improvement and keeps decreasing as the testing continues until it becomes a steady value indicating the shift to the random failure mode. In the present study, we consider how the reliability is improved by testing. We carry out a Monte Carlo Simulation to simulate the stochastic process where a defect is detected by each test. At each phase of testing, we judge whether a defect is detected or not by a random number. The overall test time is calculated and compared to the final reliability that depends on how many of latent defect remain undetected. The simulation result shows repeating a short cycle of testing is effective to obtain relatively high reliability with less testing time.

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Low cost thermal-vacuum system for the development of very small spacecraft 査読有り

Shimizu T., Motohata T., Masui H., Iwata M., Cho M., Finnholm J., Kestila A.

Proceedings of the International Astronautical Congress, IAC 8 5903 - 5906 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright ©2014 by the International Astronautical Federation. All rights reserved. Simulated space environments are necessary for validating the functionality of spacecraft and/or payloads during their development phase. A thermal-vacuum chamber is a key space environment simulator. Conventional chambers provide a high vacuum environment as well as thermal cycle environments that provide conditions similar to those encountered in space. However, even small such chambers are expensive, and are often beyond the budget of a university-based space project. In addition, the need to use liquid nitrogen coolant adds an additional high running cost. For this reason, we developed a small thermal vacuum test facility that costs less than 2000USD and which uses solid-state Peltier heaters/coolers.

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In-orbit demonstration of passive electron-emitting film for mitigation of spacecraft charging 査読有り

Tanaka A., Khan A., Iwata M., Toyoda K., Cho M., Tsuruda Y.

Proceedings of the International Astronautical Congress, IAC 11 8041 - 8046 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Satellite is greatly affected by the space environment and one of these effects is satellite charging. A passive electron emitter has been developed for satellite charging mitigation. In 2012, emission of electron from this emitter has been confirmed by a high voltage technology demonstration satellite, 'Horyu-II', made by Kyushu Institute of Technology. However, due to insufficient data and longer time resolution, repeated emission has yet to be confirmed. In order to have more data in the shorter time resolution, this emitter has been mounted on a small satellite, named 'Hodoyoshi-3' and 'Hodoyoshi-4' made by Tokyo University, passing through the aurora zone, similar to 'Horyu-II'. Functioning of this emitter and related circuitry for measuring emission current and surface potential on the flight model (FM) of 'Hodoyoshi-4', ground operation has been confirmed. Sampling rate of emission current measurement of 'Horyu-2' was 4 minutes, whereas for 'Hodoyoshi-4' it is one second only. Therefore, we expect much better and reliable information.

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ISO standard draft "design qualification and acceptance tests of small-scale satellites and units seeking low-cost and fast-delivery" 査読有り

Cho M.

Proceedings of the International Astronautical Congress, IAC 6 3966 - 3970 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2014 by MENGU CHO. There is an increasing demand of small-scale (small/micro/nano/pico) satellite development and utilization worldwide. The low success rate of small-scale satellites, however, may jeopardize their commercial use. A certain set of tests is necessary to improve their reliability to an acceptance level suitable for commercial investment. At the same time, applying the same test requirements and methods as those applied to traditional large/medium satellites will nullify the low-cost and fast-delivery advantages possessed by small-scale satellites. A new international standard has been developed and proposed to ISO/TC20/SC14. The standard describes test requirements and test methods to qualify the design and manufacturing methods of small-scale satellites and their units, and to accept the final products. Their mass and size is, but not limited to, typically less than 50kg and 50cm, respectively. The standard places emphasis on achieving reliability against infant mortality after the launch while maintaining low-cost and fast-delivery. Since 2011, an international collaborative effort has been carried out to develop the standard draft. The standard draft is currently registered as ISO/CDC-19683. This paper introduces the content of the standard draft.

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Challenges and opportunities of UNISEC-Global 査読有り

Kawashima R., Mengu C., Ibrahim M.

Proceedings of the International Astronautical Congress, IAC 12 8472 - 8476 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright ©2014 by the International Astronautical Federation. All rights reserved. The Global University Space Engineering Consortium (UNISEC-Global) has been established in November 2013 with "VISION 2020-100" that aims to create a world where university students can participate in practical space projects in more than 100 countries by the end of 2020. Recently, the number of universities and countries/regions are getting interested in participating in the UNISEC activities. In this paper, the background, vision, mission, structure, implementation, local chapter and status-quo of the UNISE-Global are introduced firstly, and then merits and difficulties in establishing local chapters are described, followed by discussion on challenges and opportunities of the UNISEC-Global.

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Basic research on radiation tests suitable for nano-satellites 査読有り

Tomioka T., Masui H., Cho M., Takamiya K.

Proceedings of the International Astronautical Congress, IAC 11 8048 - 8051 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In recent years, many nano-satellites are being developed in universities and private enterprises due to low cost and short development period. Therefore, commercial off the selves (COTS) ICs are often used in the nano-satellite projects. However, COTS ICs are not designed for space usages. It may breakdown due to strong radiation dose in the space. Therefore, radiation durability test should be performed before the satellite launch. Generally speaking, in the space radiation damage is mainly due to protons. To perform the radiation test, an accelerator is required that is expensive and needs long preparation time. Acquiring this type of test facility is against the concept of nano-satellite concept: 'Low cost and Fast delivery'. The purpose of this research is to establish a suitable radiation testing method and evaluate it as a standard for nano-satellites. It has been focused on Californium-252 ( 252 Cf) as an alternative source radiation that is a radioisotope emits heavy ions continuously. In this research, the bombardment target is a microprocessor (H8/36057) used in Horyu-2, a 30cm cubic nano-satellite developed by Kyushu Institute of Technology, Japan. Horyu-2 was launched on 18 th May 2012. One of the main abnormal phenomena observed on board microprocessor was caused by radiation and that was Single-Event-Latchup (SEL). When proton like particle strikes on a semiconductor surface, many charges are generated, named as SEL, which generates over-current in the IC and causes failure. Up to now (10 th September, 2014), SEL was occurred 5 times on the H8/36057 on board Horyu-2. By using the 252 Cf radiation system on H8/36057 microprocessor, similar situation was simulated to reveal the radiation effect on Horyu-2. First, SEL occurrence probability was calculated when single particle struck on the IC surface followed by proton flux with LET. Finally, on orbit SEL occurrence cross-section was calculated. Thus on orbit radiation resistance on microprocessor (H8/36057) can be estimated by 252 Cf using as a radiation source.

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Total electron emission yield measurement of insulating materials due to different temperatures 査読有り

Miyahara A., Wu J., Khan A., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 8 5867 - 5872 2014年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Copyright © 2014 by KYUSHU INSTITUTE OF TECHNOLOGY. Electron induced secondary electron emission from space insulator is a very important factor in understanding spacecraft charging behaviour. Due to the injection of primary electrons and the emission of secondary electrons in the surface layer of insulator, the target surface will be negatively or positively charged. Additionally, the electron emission yield of the spacecraft surface materials is highly dependent on space environments, such as the temperature variation. In our tests, we chose the polyimide film (Kapton 100H) as the research object, and used a single short, low-density pulsed beam, and also developed a scanning method for the total electron emission yield (TEEY) measurement, which can avoid surface potential influence for insulating materials. Moreover for the TEEY system, we installed a heater for high temperature (around 100°C) and the shroud by using liquid nitrogen for low temperature (around -50°C). Under this experimental situation, TEEY of polyimide films of room, high and low temperature was tested respectively. The conductivity variation of the polyimide film due to the different temperatures was considered to influence TEEY.

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Effects of Energetic Electron and Proton Irradiation on Electron Emission Yield of Polyimide Induced by Electron and Photon　掲載年月不明　（共著）査読有り

J. Wu, A. Miyahara, A. R. Khan, M. Iwata, K. Toyoda, M. Cho, X. Q. Zheng

Special Issue of ISTS, Transactions of Japan Society for Aeronautical and Space Science, Aerospace Technology 2014年01月

Evolutionary approach for Space Science Education Development in Africa（共著）査読有り

Muhammad ALKALI, Celina Gana, Danlami Idrisu, Mengu Cho

IOSR Journal of Research & Method in Education (IOSR-JRME) 4 ( 1 ) 22 - 27 2014年01月

UNISECの国際展開 : ビジョン・成果・将来展望(<特集>NPO大学宇宙工学コンソーシアムUNISECの軌跡と展望第2回) 査読有り

川島レイ, 趙孟佑, 宮崎康行, 佐原宏典, 安藤恵美子

日本航空宇宙学会誌 ( 一般社団法人日本航空宇宙学会 ) 62 ( 10 ) 331 - 336 2014年01月

記述言語：日本語掲載種別：研究論文（学術雑誌）

大学宇宙工学コンソーシアム(University Space Engineering Consortium:UNISEC)は10年余にわたる国内高専・大学への実践的宇宙開発の支援を経て,宇宙ハンズオントレーニングの有用性・有効性を確信し,活動を宇宙開発新興国を含む他地域に広げるべく,2011年に国際委員会を組織した.国際向けの活動としては,超小型衛星のミッションアイディア国際コンテスト開催,海外の新興国への衛星開発教育の実践,超小型衛星シンポジウムの事務局運営などがある.UNISECでは,2020年までに100以上の国で大学生が実践的宇宙開発に参加できるような世界を作ろうという「VISION 2020-100」を発表し,世界各地にUNISECのような大学連携組織を作り,それらの組織を横断的につなぐUNISEC-Globalを設立しようという提案を国連の会議等で行い,2013年11月には,第1回UNISEC世界大会(The 1st UNISEC-Global Meeting)を実施し,UNISEC-Globalの設立が宣言された.本稿では,UNISEC国際展開の経緯と成果およびその将来展望,課題について考察する.

DOI： 10.14822/kjsass.62.10_331

その他リンク： https://ci.nii.ac.jp/naid/110009863270

Ground Tests and In-Orbit Results for the Horyu-II Nanosatellite Power System 査読有り

OKADA Kazuya, SERI Yuki, SHIBAGAKI Ryunosuke, Satellite Project Kyutech, MASUI Hirokazu, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( 一般社団法人日本航空宇宙学会 ) 12 ( 29 ) Tf_49 - Tf_56 2014年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The Kyutech (Kyushu Institute of Technology) Satellite Project developed a high-voltage demonstration satellite called "Horyu-II" between 2010 and 2012. Horyu-II is a nanosatellite 350 mm x 310 mm x 315 mm (X*Y*Z) in size, with a mass of only 7.1 kg. This satellite was launched on May 18, 2012 as a piggy-back payload of the 21st H-IIA launch. Its missions are the demonstration of high-voltage technology in orbit, mitigation of electrostatic discharge (ESD), and so on. In this paper, we describe the design of the power system and its verification through various ground tests. The power system is equipped with a thin-film double-junction GaAs solar cell, with an efficiency of 20%, as the primary power source for the first time in orbit. The satellite also carries Ni-MH batteries for power storage. The power system architecture was simplified as much as possible with failure prevention mechanisms, such as over-current protection and various switches related to safety and debris mitigation. We present the analysis of the telemetry data obtained after the launch and validate the effectiveness of the design and verification processes.

DOI： 10.2322/tastj.12.Tf_49

その他リンク： https://ci.nii.ac.jp/naid/130004699597

Erratum for "Laboratory Tests to Standardize Environment Test Conditions of Micro/Nano Satellite Units" [Trans. JSASS Aerospace Tech. Japan Vol. 12, No. ists29, pp. Pf_1-Pf_10, 2014] 査読有り

BATSUREN Amgalanbat, TOMIDA Kenta, HATAMURA Toru, MASUI Hirokazu, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( 日本航空宇宙学会 ) 12 ( 29 ) Pf_39 - Pf_40 2014年01月

Effects of Energetic Electron and Proton Irradiation on Electron Emission Yield of Polyimide Induced by Electron and Photon 査読有り

WU Jiang, MIYAHARA Akira, KHAN Arifur, IWATA Minoru, TOYODA Kazuhiro, CHO Mengu, ZHENG Xiaoquan

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( 一般社団法人日本航空宇宙学会 ) 12 ( 29 ) Pr_13 - Pr_19 2014年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

As the electron emission yield induced by electron and photon plays a key role in surface potential of spacecraft materials, the ground based degradations including 500 keV electron and 50 keV proton irradiation with 4 different fluences were conducted for the polyimide film separately. Based on the developed measuring systems, the comparative measurements of total electron emission yield and photoelectron emission yield were carried out for the virgin and degraded polyimide samples respectively. The total electron emission yield and photoelectron emission yield tended to have different variation tendency after high energy electron and proton irradiation. The Monte-Carlo analysis software Casino and SRIM were used to analysis the distribution and stopping power of electron and proton respectively. According to the measurement results and analysis, the free radicals caused by irradiation was considered to be the main effect for polyimide films, which can primarily reveal the degradation mechanism of energetic electron and proton on the emission yield of polyimide.

DOI： 10.2322/tastj.12.Pr_13

その他リンク： https://ci.nii.ac.jp/naid/130004548652

Discharge Observation on Antenna Surface Radiating High-power Microwaves in Simulated Space Environment 査読有り

WOO Hyounggwan, KHAN Arifur R., MASUI Hirokazu, CHO Mengu, MIYAKAWA Takehiro, FUJITA Tatsuhito

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( 日本航空宇宙学会 ) 12 ( 0 ) 11 - 19 2014年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

The space solar power system (SSPS) transfers enormous amounts of electrical energy through microwaves. When high-power microwaves are irradiated from an antenna in a LEO plasma environment, there is a concern about discharge caused by interaction between the plasma and the microwaves. There has been no experimental observation of such an interaction phenomenon. Verification experiments are essential for SSPS to become a reality. We examine whether discharge or related phenomena occur or not on patch antennas under various conditions in the laboratory. We verify the hypothesis of discharge inception that the discharge is caused by multipactoring and breakdown of the outgas product. We compute the minimum electric field for the discharge inception.

DOI： 10.2322/tastj.12.11

その他リンク： https://ci.nii.ac.jp/naid/130003395403

Time and Space Redundancy Fault Tolerance Trade-offs for FPGA Based Single and Multicore Designs 査読有り

IBRAHIM Mohamed Mahmoud, ASAMI Kenichi, CHO Mengu

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( 一般社団法人日本航空宇宙学会 ) 12 ( 29 ) Pj_15 - Pj_24 2014年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

This paper investigates the gains and losses in terms of power, area, reliability, and speed when applying time redundancy fault tolerance techniques on single core designs compared to space redundancy fault tolerance techniques applied to multi-core designs. The system is developed on the virtex5 FPGA from Xilinx, it uses 65nm technology with a relatively moderate to high static power consumption. The system consists of two design alternatives. The first is a single core embedded processing system that applies time redundancy fault tolerance through execution repetition to perform self-check pointing through consensus. The second system is built from 3 soft IP core processors which perform a space redundancy approach through Triple-Modular-Redundancy (TMR) with feedback among the processors. The performance of both systems is evaluated in terms of the execution speed and latency due to fault tolerance techniques compared to the non-fault tolerant system.

DOI： 10.2322/tastj.12.Pj_15

その他リンク： https://ci.nii.ac.jp/naid/130004706673

Total electron emission yields of typical polymers 査読有り

Chen Y., Wu J., Cho M., Toyoda K.

Proceedings of IEEE International Conference on Solid Dielectrics, ICSD 752 - 755 2013年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In this paper, a pulsed scanning method for the total electron emission yield measurement of insulating materials is proposed. A total electron detector with big hollow space and insulating spacer, and a pulsed yield scanning measurement system is recommended. This method can avoid influence from the charged surface of the insulating material. Using the system, the total secondary electron emission yields of several typical polymers, such as, PA, PS, PI, PTFE, HDPE, PC, PMMA, PEEK, PET, UHMW-PE, have been reported, as induced by a 30 microsecond pulse of primary electrons with ∼ 20 nA incident beam current and energies up to 2500 eV. © 2013 IEEE.

DOI： 10.1109/ICSD.2013.6619757

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84891617612&origin=inward

Vacuum-proof characteristic test of the adhesive for asteroid sample return 査読有り

Honda K., Iwata M., Cho M., Okamoto C., Yano H.

European Space Agency, (Special Publication) ESA SP 705 SP 2013年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The asteroid probe "Hayabusa (MUSES-C)" was launched 011 May 9. 2003. JAXA has been examining the sample return mechanism for a next-generation asteroid probe, by using adhesive. A next generation asteroid probe requires long period of time from launch to return. Moreover, it is a deep concern whether the functioning of an adhesive continues under the space harsh environment. Therefore, the evaluation of the space environment that resistant adhesive should be done by simulating the space environment before launch. The purpose of this research is to evaluate the life of adhesive going to be used for the sample collection and return from an asteroid simulating the space environment in ground test. Copyright © 2013 European Space Agency.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84892659953&origin=inward

Development of Mission Payloads onboard High Voltage Technology Demonstration Satellite HORYU-I （共著）I 査読有り

Tatsuya Yoke, Shunsuke Iwai, Arifur Khan, Hirokazu Masui, Minoru Iwata, Kazuhiro Toyoda, Mengu Cho

IEEE Transactions on Plasma Science 41 ( 12 ) 3477 - 3486 2013年12月

Comparison of low Earth orbit wake current collection simulations using Nascap-2k, SPIS, MUSCAT and computer codes　（共著）査読有り

V.A. Davis, M.J. Mandell, D.C. Cooke, A. Wheelock, J.-C. Mateo-Velez, J.-F. Roussel, D. Payan, M. Cho, K. Koga

IEEE Transaction on Plasma Science 41 ( 12 ) 3303 - 3309 2013年12月

Investigation Into Surface Potential Decay of Polyimide by Unipolar Charge Transport Model（共著）査読有り

Daomin Min, Shengtao Li, Mengu Cho, Arifur R. Khan

IEEE Transaction on Plasma Science 41 ( 12 ) 3349 - 3358 2013年12月

Total Electron Emission Yield Measurement of Solid Materials by A Scanning Small Detector 査読有り

Yu Chen, Jiang Wu, Ryuta Kunimitsu, Andy Gray, Kazuhiro Toyoda, Mengu Cho

IEEE Transaction on Plasma Scienc 41 ( 12 ) 3558 - 3564 2013年12月

Development of a Very Small on-Board Oscilloscope for a Cube-Satellite HORYU-3（共著）査読有り

Tatsuo Shimizu, Hiroshi Fukuda, Shota Hidaka, Shunsuke Iwai, Kazuhiro Toyoda, Mengu Cho

5th Nano-Satellite Symposium 2013年11月

Overview of Nano/Micro Satellite for Environmental Testing in CeNT（共著）査読有り

Hirokazu Masui, Toru Hatamura, Mengu Cho

5th Nano-Satellite Symposium 2013年11月

Development of a shock test method suitable for Nano-Satellites; Performance evaluation（共著）査読有り

Toru Hatamura, Shingo Kimoto, Hirokazu Masui, Mengu Cho, Kazuo Maeno

5th Nano-Satellite Symposium 2013年11月

Testing it’s practicability as power storage unit of a nano-satellite（共著）査読有り

Muhammad ALKALI, Takuya MOTAHATA, Tatsuo SHIMIZU, Hirokazu MASUI, Mengu CHO

5th Nano-Satellite Symposium 2013年11月

Design Concept of Horyu-V The Space Environment Explorer（共著）査読有り

M.M. Ibrahim, A. Batsuren, M. Alkali, M. Nori, P. Ammarin, P. Faure, M. Cho

The 5th Nano-Satellite Symposium 2013年11月

Reliability Growth of Small-scale Satellites through Testing（共著）査読有り

Mengu Cho, M. Ibrahim

The 5th Nano-Satellite Symposium 2013年11月

Development of a Very Small on-Board Oscilloscope for a Cube-Satellite HORYU-3（共著）査読有り

T. Shimizu, S. Hidaka, M.M. Ibrahim, S. Iwai, K. Toyoda, H. Masui, M. Cho

The 5th Nano-Satellite Symposium 2013年11月

Basic Research on Vibration Test Standardization for Small-scale Satellites（共著）査読有り

Amgalanbat Batsuren, Toru Hatamura, Hirokazu Masui, Mengu Cho

5th Nano-Satellite Symposium 2013年11月

Radiation test for Horyu3’s bus-system using Californium252（共著）査読有り

Yuta Okumura, Hirokazu Masui, Cho Mengu

The 5th Nano-satellite Symposium 2013年11月

Thermal distribution of typical structure specialized in 50cm class satellite（共著）査読有り

Yuki Seri, Toru Hatamura, Hirokazu Masui, Mengu Cho

The 5th Nano-Satellite Symposium 2013年11月

Distribution measurement of Nano-Satellite components for shock level estimation（共著）査読有り

Shingo Kimoto, Toru Hatamura, Hirokazu Masui, Mengu Cho

5th Nano-Satellite Symposium 2013年11月

Horyu-V the Space Environment Explorer Satellite ? Strategic Auditing, United Nations/United Arab Emirates Symposium on Basic Space Technology（共著）査読有り

Mohamed Mahmoud Ibrahim, Horyu-V team, Mengu Cho

Small Satellite Missions for Developing Space Nations 2013年10月

Development of Vacuum Arc Thruster for Nano-Satellite（共著）査読有り

Shingo Fuchikami, Masayoshi Nakamoto, Kazuhiro Toyoda, Mengu Cho

33rd International Electric Propulsion Conference 2013年10月

Evaluation of SRAM based FPGA performance by simulating SEU through fault injection 査読有り

Ibrahim M., Asami K., Cho M.

RAST 2013 - Proceedings of 6th International Conference on Recent Advances in Space Technologies 649 - 654 2013年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

This paper presents the technique and results of Single Event Upsets fault injection in the configuration bit-stream of SRAM-based FPGAs through partial reconfiguration of configuration frames. The Xilinx Virtex5 LX50 is used in the experiments. The Single Event Upset controller macro is used injecting faults to random locations of the FPGA bit-stream. The effects were studied on a design consisting of 4 embedded processor systems implemented in the FPGA. MATLAB is used for developing the external fault injection control environment. © 2013 IEEE.

DOI： 10.1109/RAST.2013.6581290

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84883891789&origin=inward

Nano-satellite development project and space engineering education at Kyushu Institute of Technology 査読有り

Cho M., Masui H., Satellite K.

RAST 2013 - Proceedings of 6th International Conference on Recent Advances in Space Technologies 1059 - 1063 2013年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Students of Kyushu Institute of Technology successfully developed a 7kg nanosatellite, HORYU-II. The satellite was tested extensively at Center for Nanosatellite Testing. There are many lessons learned through its designing, development, testing and operation to be shared among the university satellite community. Since 2013, the university will launch a new post-graduate program, Space Engineering International Course, where Japanese and foreign students learn the basic space technology through hands-on experience gained by participating in a satellite project utilizing space engineering research infrastructure within the campus. The program is also carried out as United Nations/Japan long term fellowship programme to assist capacity building of basic space technology in countries that have little experience in satellite development. Selected students will be awarded Japanese government scholarship. This paper describes the space engineering education at Kyushu Institute of Technology. © 2013 IEEE.

DOI： 10.1109/RAST.2013.6581159

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84883864032&origin=inward

Peripheral electronics prototype of super-capacitor energy storage for small satellites 査読有り

Shimizu T., Underwood C., Cho M.

11th International Energy Conversion Engineering Conference 2013年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Small satellites, weighting between 100 to 200 kg, were considered as a case study and their use of super-capacitors was assessed in this paper. Such satellites have witnessed an increasing use for various space applications including remote sensing constellations and technology demonstrations. However, their current maximum power supply capability ranges between 70 and 200W. This power range has become insufficient for accommodating wide range of recent payloads on small satellites, and this low power has become a limitation of such small satellites. Super-capacitors are low mass and low volume energy storage mediums that have an ability to supply high electrical power. Compared with conventional chemical batteries, they are able to supply high power at high efficiency without damaging its life. This is an order of magnitude better than the power delivery capability of conventional batteries, and would enable micro-satellites to operate payload with l-2kw power consumptions for a minute or so. This high power capability makes small satellites more attractive to wider applications such as radar imaging and new technology demonstrations which used to operate on a larger satellite platform, and may leads to a breakthrough in terms of platform choice for payloads. This paper discusses feasibility of the super-capacitor based power system through a prototype development.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84883546614&origin=inward

Anomaly investigation of HORYU-II and lessons learned（共著）査読有り

Yuta Okumura, Kyutech Satellite Project, Hirokazu Masui, Mengu Cho

The 64th International Astronautical Cogress 2013年09月

Lessons Learned and a New Project: Measurement of arcing current on HORYU-III" satellite"( 共著）査読有り

Yuta Okumura,Kyutech Satellite Team, Tatsuo Shimizu, Hirokazu Masui, Mengu Cho

Tsinghua University IAF-SUAC International Student Workshop 2013年09月

Mission Results of High Voltage Technology Demonstration Statellite Horyu-2""（共著）査読有り

Shunsuke Iwai, Kyutech Satellite Project, Arifur Rahaman Khan, Hirokazu Masui, Minoru Iwata,Kazuhiro Toyoda, Mengu Cho

64th International Astronautical Congress 2013年09月

MITIGATION METHOD OF PREVENTING SECONDARY ARCING ON SOLAR ARRAY BY USING CAPACITOR AND INDUCTOR（共著）査読有り

Ishio Haruta, Tatsuo Shimizu, Kazuhiro Toyoda, Mengu Cho

64th International Astronautical Congress 2013年09月

High voltage Flight Experiment In Low Earth Orbit（共著）査読有り

Shunsuke Iwai, Justin J Likar, Teppei Okumura, Hirokazu Masui, Kazuhiro toyoda, Mengu Cho

Tsinghua University IAF-SUAC International Student Workshop 2013年09月

300V direct drive vacuum arc thruster for nano-satellite 査読有り

Nakamoto M., Fuchikami S., Toyoda K., Cho M.

51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 2013年08月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Vacuum arc thruster is very light and small for installed nano-satellite, and it operates without igniter. The thruster takes use of discharging in triple (insulator, conductor and vacuum) junction. The vacuum arc discharge releases the metal vapor, which can result in producing thrust. This research investigated on basic performance of vacuum arc thruster and EM development. © 2013 by the American Institute of Aeronautics and Astronautics, Inc.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84881419615&origin=inward

On-orbit data analysis of high voltage technology demonstration satellite HORYU-II 査読有り

Iwai S., Yoke T., Masui H., Iwata M., Toyoda K., Cho M.

51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 2013年08月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The High Voltage Technology Demonstration Satellite named HORYU-II is a nano-satellite (30cm cubic shape, 7kg) successfully developed by students at Kyushu Institute of Technology. The main purpose of this satellite is orbital demonstration of the feasibility the forthcoming space high voltage technologies. The International Space Station (ISS) generates the highest voltage, 160V, among all of the current active space systems. HORYU-II aims at being the world's first satellite to generate a voltage of 300V by using solar array, which is significantly higher voltage than the one generated on board the ISS. However, due to the generation of the high voltage, Electrostatic Discharges (ESDs) are more likely to occur. Therefore, HORYU-II also aims at performing a demonstration of ESD mitigation technology. HORYU-II was launched by a H-2A rocket on May 18, 2012. HORYU-II is functioning normally and data from orbit have recently been recorded and data analysis is under way. Results of the analysis will be presented in detail at the conference. © 2013 by Kyushu Institute of Technology.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84881448877&origin=inward

Testing of Micro/Nano Satellites and Their On-orbit Performance（共著）査読有り

Hirokazu Masui, Toru Hatamura, Mengu Cho

27th Small Satellite Conference 2013年08月

Mission Results and Anomaly Investigation of HORYU-II（共著）査読有り

Yuki Seri, KIT Satellite Project, Hirokazu Masui, Mengu Cho

Annual AIAA/USU Conference on Small Satellites, Utah State University 2013年08月

Peripheral Electronics Prototype of Super-Capacitor Energy Storage for Small Satellites（共著）査読有り

Tatsuo Shimizu, Craig Underwood, Mengu Cho

11th International Energy Conversion Engineering Conference 2013年07月

Reconfigurable fault tolerant avionics system 査読有り

Ibrahim M., Asami K., Cho M.

IEEE Aerospace Conference Proceedings 2013年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

This paper presents the design of a reconfigurable avionics system based on modern Static Random Access Memory (SRAM)-based Field Programmable Gate Array (FPGA) to be used in future generations of nano satellites. A major concern in satellite systems and especially nano satellites is to build robust systems with low-power consumption profiles. The system is designed to be flexible by providing the capability of reconfiguring itself based on its orbital position. As Single Event Upsets (SEU) do not have the same severity and intensity in all orbital locations, having the maximum at the South Atlantic Anomaly (SAA) and the polar cusps, the system does not have to be fully protected all the time in its orbit. An acceptable level of protection against high-energy cosmic rays and charged particles roaming in space is provided within the majority of the orbit through software fault tolerance. Check pointing and roll back, besides control flow assertions, is used for that level of protection. In the minority part of the orbit where severe SEUs are expected to exist, a reconfiguration for the system FPGA is initiated where the processor systems are triplicated and protection through Triple Modular Redundancy (TMR) with feedback is provided. This technique of reconfiguring the system as per the level of the threat expected from SEU-induced faults helps in reducing the average dynamic power consumption of the system to one-third of its maximum. This technique can be viewed as a smart protection through system reconfiguration. The system is built on the commercial version of the (XC5VLX50) Xilinx Virtex5 FPGA on bulk silicon with 324 IO. Simulations of orbit SEU rates were carried out using the SPENVIS web-based software package. © 2013 IEEE.

DOI： 10.1109/AERO.2013.6497203

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84878733690&origin=inward

Performance Inprovement of Electron-emitting Film for Spacecraft Charging Mitigation（共著）査読有り

Atomu Tanaka, Naoki Matsumoto, Arifur Rahman Khan, Minoru Iwata, Kazuhiro Toyoda, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

Total Electron Emission Yield Measurement of Polyimide at Different Temperatures (共著）査読有り

Akira Miyahara, Jiang Wu, Minoru Iwata, Kazuhiro Toyoda, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

Effect of Energetic Electron and Proton Irradiation on Electron Emission Yield of Polyimide Induced by Electron and Photon"（共著）査読有り

Jiang Wu, Akira Miyahara, Minoru Iwata, Kazuhiro Toyoda, Mengu Cho, Xiaoquan Zheng

29th International Symposium on Space Technology and Science 2013年06月

Comparison of Thermal Distribution within a 50 cm class satellite in Vacuum and Atmosphere Environment（共著）査読有り

Hirokazu Masui, Yuki Seri, Toru Hatamura, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

Basic Research on Vibration Test Level for Nanosatellite Components（共著）査読有り

Kenta Tomida, Amgalanbat Batsuren, Toru Hatamura, Hirokazu Masui, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

Development of a shock test method suitable for nano-satellites; basic study（共著）査読有り

Toru Hatamura, Shingo Kimoto, Hirokazu Masui, Mengu Cho, Kazuo Maeno

29th International Symposium on Space Technology and Science 2013年06月

Effects of Energetic Electron and Proton Irradiation on Electron Emission Yield of Polyimide Induced by Electron and Photon（共著）査読有り

J. Wu, A. Miyahara, A. R. Khan, M. Iwata, K. Toyoda, M. Cho, X. Q. Zheng

29th International Symposium on Space Technology and Science 2013年06月

Time and Space Redundancy Fault Tolerance Trade-offs for FPGA Based Single and Multicore Designs（共著）査読有り

Mohamed Mahmoud Ibrahim, Kenichi Asami, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

LEO Single Event Upset Emulator for Validation of FPGA Based Avionics Systems（共著）査読有り

Mohamed Mahmoud Ibrahim, Kenichi Asami, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

Laboratory Test of Vibration of Micro/Nano Satellite for Environment Test Standardization(共著）査読有り

Amgalanbat Batsuren, Toru Hatamura, Hirokazu Masui, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

Results of 300V Photovoltaic Power generation Mission Onboard Horyu-2（共著）査読有り

Shunsuke Iwai, Kyutech Satellite Project, Hirokazu Masui, Minoru Iwata,Kazuhiro Toyoda, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

Total Electron Emission Yield Measurement of Polyimide Due to Different Temperatures（共著）査読有り

Akira Miyahara, Wu Jiang, Kazuhiro Toyoda, Mengu Cho

29th International Symposium on Space Technology and Science , Nagoya, Japan 2013年06月

On-orbit results of the power system on-board Nano-satellite Horyu-II（共著）査読有り

Kazuya OKADA, Yuki SERI, Ryunosuke Shibagaki, Kyutech Satellite Project, Hirokazu MASUI, Mengu CHO

29th International Symposium on Space Technology and Science, Nagoya, Japan 2013年06月

Charging/Discharging Test of Lithium-Ion Battery using a Nano-Satellite Power System Made for Nickel-Metal Hydride Battery（共著）査読有り

Takuya Motohata, Kazuya Okada, Hirokazu Masui, Yasuhiro Akahoshi, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

In-orbit demonstration of spacecraft charging mitigation of passive electron-emitting film（共著）査読有り

Naoki Matsumoto, Atomu Tanaka, Arifur R Khan, Minoru Iwata, Kazuhiro Toyoda, Mengu Cho

International Symposium on Space Technology and Science 2013年06月

Development of Vacuum Arc Thruster for Nano-Satellite in Low Earth Orbit Plasma　Environment（共著）査読有り

Shingo Fuchikami, Masayoshi Nakamoto, Kazuhiro Toyoda, Mengu Cho

29th International Symposium on Space Technology and Science 2013年06月

Evaluation of SRAM based FPGA Performance by Simulating SEU through Fault Injection（共著）査読有り

Mohamed Mahmoud Ibrahim, Kenichi Asami, Mengu Cho

RAST-2013 2013年06月

Selection of the Commercial-Off-the-Shelf Antistatic Coating and Its Applicability for Space-Use Solar Array（共著）査読有り

Minoru Iwata, Akitoshi Takahashi, Musashi Sakamoto, Mengu Cho, Ryo Muraguchi

Transactions of The Japan Society for Aeronautical and Space Sciences 57 ( 3 ) 153 - 159 2013年04月

In-orbit Demonstration of Newly Developed Passive Electron-emitting Film for Spacecraft Charging Mitigation（共著）査読有り

Arifur R. Khan, Minoru Iwata, Kazuhiro Toyoda, Mengu Cho, Yuta Takaki

Journal of Spacecraft and Rockets 50 ( 4 ) 853 - 859 2013年03月

Investigation on Space Environmental Degradation Effects of Solar Cell Coverglass（共著）査読有り

Yu Chen, Jiang Wu, Teppei Okumura, Masato Takahashi, Taishi Endo, Minoru Iwata, Kazuhiro Toyoda, Mengu Cho

IEEE Transactions on Plasma Science 41 ( 12 ) 3471 - 3476 2013年03月

Special issue on spacecraft charging technology 2013

Cho M., Cooke D., Ferguson D., Garrett H., Hilgers A., Lai S., Roussel J., Toyoda K., Wheelock A.

IEEE Transactions on Plasma Science ( IEEE Transactions on Plasma Science ) 41 ( 12 ) 2013年01月

Mitigation method of preventing secondary arcing on solar array by using capacitor and inductor 査読有り

Haruta I., Shimizu T., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 12 9397 - 9403 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Recently, the trend of spacecraft designers has led to the tendency of making larger and multifunctional satellites. In order to achieve the growing demands, the development of a large satellite bus is indispensable. However, electrical discharge accidents have increasingly come to occur on the solar arrays due to the higher bus voltage of any satellite. An electrical discharge on the solar array not only decreases the generating power but also can even halt operation of the satellite entirely. During electrical discharges, various arcing are possible, among which sustained arc is the most detrimental to the satellite. At present, grouting (adhesive is buried between solar cells to which high voltage is applied) is practiced as a mitigation method of sustained arc. However, this method has several disadvantages. Therefore, the development of a new mitigation method is requested. In this paper, we report the effect of mitigation method for sustained arc on solar array, by inserting capacitor and inductor into sustained arc circuit. It is confirmed that sustained arcs were oscillated by the capacitor (i.e. several hundred nF). Therefore, if the oscillation is sufficiently big, sustained arcs can be mitigated. In addition, this paper discusses a relation between flashover current and secondary arc. From the experimental results, when flashover is short, arc current to vibrate and it is suppressed. When flashover is long, arc current can't cut and it isn't suppressed. But, by increasing the capacitance of the capacitor, it was possible to accommodate long flashover discharge. Copyright ©2013 by the International Astronautical Federation.

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Mission results of high voltage technology demonstration satellite "HORYU-2 査読有り

Iwai S., Khan A., Masui H., Iwata M., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 12 9377 - 9391 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The World's largest spacecraft bus voltage is the International Space Station (ISS) with a bias voltage of 160V. We have investigated a power bus able to handle higher voltage than the ISS. Electro-static discharges (ESDs) are more likely to occur when a satellite generates power at a high voltage rather than low voltage in low Earth orbit (LEO). However, high voltage generation is essential for building large space systems. Therefore, Kyushu Institute of Technology (Kyutech) is developing a high voltage generation technology that could counteract ESDs. This could be considered as a key technology for next generation spacecraft. Nano-satellites are useful and less risky tools for technology demonstration since they are faster and less expensive to develop than large satellites. Therefore, we focused on nano-satellite development to demonstrate Kyutech's advanced high voltage generation technology. All of the on-orbit high voltage tests have been demonstrated by using a DC/DC converter to adapt the high voltage generated by the solar array. This was a World premiere as no high voltage tests had previously been performed in space using solar arrays. To demonstrate the feasibility of on-orbit high voltage generation, we developed a High Voltage Technology Demonstration Satellite named HORYU-2. The mission consisted of 300V generation without causing arcing, and contribution to the practical development of 1MW class spacecraft. On May 18, 2012, HORYU-2 was launched by the H-2A rocket number 21. HORYU-2 has been operated from Kyutech's ground station, and HORYU-2's orbit was confirmed and the mission successful. For the first time in the World, 350V have been generated on-orbit without arc creation. Using two specially designed solar arrays arcing was mitigated. Regarding the sub-missions, ELF was proven to work well on-orbit, Trek measurements are currently under investigation, the SCAMP camera successfully imaged Earth, and the debris sensor has not yet detected debris impact. During the conference, we will present all mission analysis in further detail. Copyright ©2013 by the International Astronautical Federation.

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Initial results from Primary Arc effects on solar cells at LEO (PASCAL) flight experiment 査読有り

Likar J., Okumura T., Iwai S., Stone S., Gasner S., Jenkins P., Trautz K., Cho M., Lombardi R., Toyoda K.

Conference Record of the IEEE Photovoltaic Specialists Conference 3112 - 3114 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Repeated low power, or primary arcing, may adversely affect the performance of space solar cells. The cumulative effects of primary arcing on common solar cell performance parameters has been the subject of numerous ground studies in simulated plasma environments. The Primary Arc effects on Solar Cells At LEO (PASCAL) flight experiment is presently active aboard in the International Space Station (ISS) and characterizing such effects in-orbit for numerous state-of-the-art space solar cells with initial results presented herein. © 2013 IEEE.

DOI： 10.1109/PVSC.2013.6745118

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Engineering education through on-the-job training in nano-satellite for capacity building in basic space technology development 査読有り

Cho M., Polansky J., Balogh W.

Proceedings of the International Astronautical Congress, IAC 5 3824 - 3828 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Developing countries that in the past have mostly focused on applications-oriented aspects of space technology are increasingly also interested in building indigenous capacities for basic space technology development. A nano-satellite development program is an ideal first-step to establish such a basic capacity. Experience gained through on-the-job training, going through the complete cycle of designing, building and testing a satellite, is crucial to gain this capacity. To fill that demand there is a need for educational institutions to offer appropriate on-the-job training opportunities. In 2010, Kyushu Institute of Technology (Kyutech) and the United Nations Office for Outer Space Affairs launched a long-term fellowship programme on nano-satellite technologies for post-graduate level students from developing countries and countries with economies in transition. The programme has been quite successful. Every year since 2011, two students have enrolled in a Ph.D. course at Kyutech. Based on this success, the fellowship program has been expanded beginning with the class of 2013. The number of fellowship recipients has been increased from two to six. Students seeking a Master degree may also apply. To accommodate the large number of international students, Kyutech will launch a new postgraduate curriculum, the Space Engineering International Course, where students will gain extensive knowledge necessary to build basic space technology in their home countries through various lectures on space engineering in English, laboratory workshops on satellite testing, and participation in various space projects. This paper describes new development details of the fellowship program. ©2013 by the International Astronautical Federation. All rights reserved.

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Anomaly investigation of HORYU-II and lessons learned 査読有り

Okumura Y., Masui H., Cho M.

Proceedings of the International Astronautical Congress, IAC 6 4211 - 4218 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The HORYU-II nanosatellite was launched as a secondary payload on-board an H-IIA rocket on May 18, 2012 (UTC). The spacecraft was completely developed by students from Kyushu Institute of Technology starting from 2010. HORYU-II operated normally from orbit injection until June 5 when anomalies were observed in the housekeeping data. By June 30, 2012, only call signs were received. Fortunately, the satellite was able to reset and operate in steady mode, even though the battery state dropped to about 10%. This paper presents HORYU-II anomaly investigation results and the lessons learned. We carried out Fault Tree Analysis (FTA) to determine failure root cause. Among the phenomena observed were: irregular housekeeping data, unresponsive Telecommands from the ground station, communication limited to call signs, and low residual battery quantity after recovery. After ground-based assessment of the spare bus system, we concluded that the anomaly cause was radiation effect on the On-Board Computer (OBC) system. Single Event Latch-up (SEL) occurrence caused over current of the Micro Controller Unit (MCU). We underestimated the radiation effect. We contrived overcurrent protection for the OBC circuit but we did not measure over current flow on the subsystem when SEL occurs. The communication system is independent of the MCU and can continuously send call signs. For this reason, we were able to receive call signs and trace the satellite even when the OBC MCU stopped operating. The power system was designed to restart when battery charge reached 0% and this was confirmed from ground testing. Copyright© (2013) by the International Astronautical Federation.

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Total electron emission yield of solar cell coverglass and optical solar reflector 査読有り

Chen Y., Wu J., Kunimitsu R., Gray A., Toyoda K., Cho M.

IEEE Transactions on Plasma Science 41 ( 12 ) 3558 - 3564 2013年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Electron-induced secondary electron (SE) emission from space insulating materials is a very important factor in understanding spacecraft charging behavior. Because of the injection of primary electrons (PEs) and the emission of SEs in the surface layer of insulating materials, the target surface can be either negatively or positively charged. In the conventional measurement methods, a single short, low-density pulsed e-beam, charge neutralization using low energy flood e-gun and UV light, and charge dissipation by heating is used. In this paper, a pulsed scanning method for the total electron emission yield measurement of insulating, semiconducting or conducting solid materials is proposed. A total electron detector with large hollow space and insulating spacer was designed, and a pulsed yield scanning measurement system was developed. This method can avoid influence from the charged surface of the insulating material. Using the system, the total SE emission yields of 200 nm thick Au coating on glass, and 11 kinds of solar cell coverglasses and optical solar reflectors produced by Qioptiq have been reported, as induced by a 30 μ s pulse of PEs with ~ 20 nA incident beam current and energies up to 2500 eV. © 1973-2012 IEEE.

DOI： 10.1109/TPS.2013.2288575

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Measurement of atomic-oxygen flux distribution 査読有り

Hisashiba T., Kuroda K., Masui H., Iwata M., Toyoda K., Cho M.

Astrophysics and Space Science Proceedings 32 597 - 606 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© Springer-Verlag Berlin Heidelberg 2013. Since material surfaces on the outside of spacecraft are exposed directly to the space environment, material having high tolerance to atomic oxygen, ultraviolet rays and radiation are preferred for long time spacecraft operation. In order to examine the influence of atomic oxygen (AO) on space grade materials, an atomic oxygen simulation chamber was developed. A system was developed that generates AO using a laser detonation method. A CO 2 gas laser (5 J) irradiates the oxygen gas in a vacuum chamber (2 MPa) to dissociate the molecular oxygen into atomic. The velocity of AO can be controlled based on the timing between the laser and the gas pulse valve that injects oxygen gas into the chamber. The AO velocity generated by this system is measured using a QMASS (Quadruple Mass Spectrometer) and found to be 8 km/s. It was necessary to measure the AO flux distribution in the chamber at the location where the material samples are exposed to AO. The AO flux distribution was evaluated by measuring the mass gain on a QCM (QuartzCrystal Micro-balance) coated with a silver film upon exposure to the AO.

DOI： 10.1007/978-3-642-30229-9_56

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Discharge Observation on Antenna Surface Radiating High Power Microwave in Simulated Space Environment　掲載年月不明　(共著）査読有り

Hyounggwan Woo, Arifur R.Khan, Hirokazu Masui, Mengu Cho, Takehiro Miyakawa, Tatsuhito Fujita

Aerospace Technology Japan (JSASS:The Japan Society for Aeronautical and Space Sciences) 12 11 - 19 2013年01月

Time and Space Redundancy Fault Tolerance Trade-offs for FPGA Based Single and Multicore Designs 掲載年月不明　( 共著）査読有り

Mohamed Mahmoud Ibrahim, Kenichi Asami, Mengu Cho

Japan Society for Aeronautical and Space Science, Transactions-special issue on ISTS 2013年01月

LEO Single Event Upset Emulator for Validation of FPGA Based Avionics Systems掲載年月不明　（共著）査読有り

Mohamed Mahmoud Ibrahim, Kenichi Asami, Mengu Cho

JSASS Transactions-special issue on ISTS-29th 2013年01月

Laboratory Test of Vibration of Micro/Nano Satellite for Environment Test Standardization 　掲載年月不明　( 共著）査読有り

Amgalanbat Batsuren, Toru Hatamura, Hirokazu Masui, Mengu Cho

Special Issue of ISTS, Transactions of Japan Society for Aeronautical and Space Science, Aerospace Technology 2013年01月

Laboratory Tests to Standardize Environment Test Conditions of Micro/Nano Satellite Units　掲載年月不明　（共著）査読有り

Amgalanbat Batsuren, Kenta Tomida, Toru Hatamura, Hirokazu Masui, Mengu Cho

Transactions of Japan Society for Aeronautical and Space Science, Aerospace Technology 2013年01月

Ground tests and on-orbit results of the power system of nano-satellite Horyu-II2　掲載年月不明　（共著）査読有り

Kazuya OKADA, Yuki SERI, Ryunosuke Shibagaki, Kyutech Satellite Project, Hirokazu MASUI and Mengu CHO

Aerospace Technology Aerospace Technology Japan 2013年01月

超小型衛星「鳳龍弐号」の試験・検証と軌道上不具合原因究明　掲載年月不明（共著）査読有り

趙孟佑、増井博一、九州工業大学衛星開発プロジェクト

航空宇宙技術 12 17 - 24 2013年01月

Design of a Multi-Processor System-on-Chip On Board Computer Using FPGA Based Soft IP Cores　掲載月日不明（共著）査読有り

Mohamed Mahmoud Ibrahim Kenichi Asami, Mengu Cho

IOSR-JCE journal 2013年01月

The use of reconfigurable FPGAs in developing reliable satellites on board computers 査読有り

Ibrahim M., Asami K., Cho M.

AIAA SPACE Conference and Exposition 2012 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The design of fault tolerant systems for space applications mandates the use of new techniques to construct robust and reliable systems. Nowadays modern Field Programmable Gate Arrays (FPGA) provide very high logic capacity and low power consumption profiles. The size, weight and thermal characteristics are acceptable even for the non-space grade category. A major trend is to use the commercial grade FPGAs to build satellite systems using fault tolerant design techniques. The commercial grade components are often state-of-art and provide faster and better performance than the well tested and approved space components. In low cost satellite missions, it is acceptable to bear some risk in return for using the widely accessible and low cost commercial grade components. In this paper we present the ongoing development of a robust embedded computer system to be used as the main on-board computer of Micro and Nano satellites at Kyushu Institute of Technology, Japan. The system makes use of the soft IP cores available for the Microblaze processors from Xilinx Inc. The Xilinx FPGAs are Static Random Access Memory (SRAM) based and do not apply the anti-fused technology. They need periodic scrubbing for the SRAM memory holding the hardware design. Xilinx introduced a reconfigurable technique to facilitate the reconfiguration of their FPGAs even while operating without affecting other parts of the design. This technique is known as partial reconfiguration, in which parts of the system will be reconfigured while the rest of the system is functioning without interruption. It provides a facility to improve the development of fault tolerant FPGA designs through read-back and then reconfiguration of faulty FPGA modules. We present our use of this technique to build a robust On-Board computer system on SRAM based FPGAs using soft Intellectual Property (IP) cores. The results of applying this technique are discussed in terms of gains, drawbacks and the effects on the overall fault tolerance performance. © 2012 by Mohamed Mahmoud Mohamed Ibrahim. Published by the American Institute of Aeronautics and Astronautics, Inc.

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Preliminary report on on-orbit experiment on high voltage technology demonstration satellite, HORYU-II 査読有り

Takahashi A., Khan A., Masui H., Iwata M., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 12 9657 - 9667 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

A cubic nano-satellite with a length of 30 cm, named HORYU-II, was developed at Kyushu Institute of Technology in Japan. HORYU-II is a demonstration satellite for high voltage technology and its two main advantages are its low cost and short time development. HORYU-II's main mission is to demonstrate the possible generation of 300V on-orbit by using spherical solar cells connected in series. This mission can be considered as the first high voltage technology demonstration in the world. To control arcing under negative 300V in space plasma, ETFE (ethylene tetra flouro ethylene) cover and semi-conductive coated solar array efficiency will be demonstrated. Along with this, charging mitigation of spacecraft by using electron emitting film, operation of commercial-off-the-shelf (COT) surface potentiometer will also be demonstrated. HORYU-II was launched by a H-IIA rocket on May 18, 2012. We have been acquiring on-orbit data and monitoring the satellite conditions. HORYU-II succeeded in generating the highest 300V photovoltaic voltage in space for the first time in the world. However, many problems were found during data collection. In this paper, the result of HORYU-II's missions is described.

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Horyu-2 educational satellite: Lessons learnt and future perspectives 査読有り

Ibrahim M., Faure P., Asami K., Cho M.

AIAA SPACE Conference and Exposition 2012 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Educational satellites are being built with many Universities and research institutes all over the world. The purpose of such satellite projects is to train and educate under graduate, graduate and post graduate students on the concepts and practices of satellite engineering. A major issue that should be studied after the project finishes is the evaluation of the project in terms of the lessons learnt. This evaluation provides the research institute or the University with the necessary feedback and guidance for future missions and research. In this paper we present an evaluation for the Horyu-2 project, a Nano-Satellite built in Kyushu Institute of Technology (Kyutech) in Japan. The evaluation is a kind of a strategic audit to judge the appropriateness and fitness of the applied strategies in educational satellite development activities at Kyutech. The study provides recommendations to maximize the benefits in future projects. It is based on interviewing all the project members and performing field surveys to carefully point out the Strengths and Weaknesses in the internal environment of the satellite development center. The external Opportunities and Threats were identified by studying several factors in the economic, social, political, legal and technological dimensions. The Strengths, Weaknesses, Opportunities and Threats were used to develop a SWOT analysis to propose and recommend future strategies. The Horyu-2 satellite experiment was studied as a model that can possibly be exported to other countries especially developing countries and countries just starting their space activities. © 2012 by Mohamed Mahmoud Mohamed Ibrahim. Published by the American Institute of Aeronautics and Astronautics, Inc.

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Fault tolerant architecture alternatives for developing nano-satellites embedded computers 査読有り

Ibrahim M., Asami K., Cho M.

AIAA SPACE Conference and Exposition 2012 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Nano-Satellites development is spreading tremendously nowadays. The fact that Nano-Satellites are of low development cost thus the risk incurred is affordable makes them the premiere choice as technology demonstrators and test beds. This satellite category is characterized with the use of Commercial-Of-The-Shelf (COTS) components, neither space approved nor radiation hardened components are usually used in its development. This paper introduces a challenge in building reliable yet low cost systems, constructed from commercially available components. Nano-Satellites should keep on using such grade of components as this gives them the unique feature of being accessible to wide category of space practitioners and universities within the limited budgets. A crucial part in any satellite system is its embedded computer system known as the On-Board computer which might carry tasks, according to the mission design, ranging from command and data handling to full control over the payload and scientific data collection. The satellite architecture either it is distributed consisting of more than one processing node or concentric consisting of one powerful computing node, still needs to apply fault tolerance design techniques to provide robustness for the system. In this paper we present a group of architecture alternatives that are considered, during our effort to develop a fault tolerant On-Board computer at Kyushu Institute of Technology, Japan. © 2012 by Mohamed Mahmoud Mohamed Ibrahim. Published by the American Institute of Aeronautics and Astronautics, Inc.

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Discharge observation on antenna surface radiating high power microwave in plasma environment 査読有り

Woo H., Khan A., Masui H., Cho M., Miyakawa T., Fujita T.

Proceedings of the International Astronautical Congress, IAC 9 7029 - 7037 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Space Solar Power System (SSPS) transfers enormous amount of electrical energy through microwave. Flight demonstration onboard a small satellite in Low Earth Orbit (LEO) is now under consideration. When a high power microwave is irradiated from antenna in LEO plasma environment, there is a concern about discharge caused by interaction between the plasma and the microwave. There has been no experimental observation on such interaction phenomenon. Verification experiment is essential for SSPS to become a reality. We have set-up an experimental system that can simulate the radiation of high power microwave under dense plasma in a vacuum chamber. A RF plasma source was installed to the chamber that we filled with Argon plasma environment of density from 1011 to 10 m' with 4eV to 6eV temperature under a back pressure of 2.6x10" Pa. A patch antenna made of Glass epoxy substrate was installed inside the chamber. The antenna was connected to a magnetron that could produce 5.8GHz microwave. We monitored the antenna surface temperature, the radiated and reflected power, the chamber pressure and others while we injected the microwave to the antenna up to 45W. We examined whether discharge or related phenomena occur or not on the patch antennas for various conditions to verify the hypothesis of discharge inception that discharge is caused by multi-pactoring and breakdown of the outgas product. Copyright © (2012) by the International Astronautical Federation.

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Special issue on spacecraft charging technologies

Cho M., Cooke D., Ferguson D., Garrett H., Hilgers A., Lai S., Roussel J., Toyoda K., Wheelock A.

IEEE Transactions on Plasma Science ( IEEE Transactions on Plasma Science ) 40 ( 9 ) 2012年09月

Guest editorial: Special issue on spacecraft charging technology 2012

Cho M., Cooke D., Ferguson D., Garrett H., Hilgers A., Lai S., Roussel J., Wheelock A.

IEEE Transactions on Plasma Science ( IEEE Transactions on Plasma Science ) 40 ( 2 PART 1 ) 2012年02月

Data analysis of the polar plasma environment for spacecraft charging analysis 査読有り

Cho M., Saito K., Hamanaga T.

62nd International Astronautical Congress 2011, IAC 2011 10 8316 - 8331 2011年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Polar Earth orbit (PEO) is a peculiar orbit where energetic auroral electrons and low-temperature ionospheric plasma coexist. There is a risk of charging and subsequent arcing in PEO. The plasma environment, namely its density and energy, is the crucial parameter for the spacecraft charging analysis. We statistically analyzed the environmental condition in PEO using the data of auroral electrons and thermal ions measured by DMSP (Defense Meteorological Satellite Program) satellites. Probability of a given combination of current densities of auroral electrons and thermal ions has been derived. The energy spectrum of the auroral electrons are also classified into several types and correlation with the thermal ions is analyzed. Combinations of the plasma parameters used by a spacecraft charging simulation software have been identified and database regarding the probability of occurrence of each combination has been formulated.

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Evaluation method of solar array panel substrate insulation against sustained arcs 査読有り

Toyoda K., Wada T., Endo T., Cho M., Hoang B., Hsieh T.

3rd AIAA Atmospheric Space Environments Conference 2011年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

A testing method for evaluating the robustness of insulation films against sustained arcs on solar array panels was developed. Metal electrodes were used to simulate solar cells. The gap length between electrodes was controlled. In this paper, five samples with various insulator thicknesses were tested with the testing method. The robustness of the insulation films was evaluated. © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

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Effect of atomic oxygen exposure on resistivity change on spacecraft insulator materials 査読有り

Noor Danish Ahrar Mundari,Arifur Rahman Khan,Masaru Chiga,Teppei Okumura,Hirokazu Masui,Minoru Iwata,Kazuhiro Toyoda,Mengu Cho

Trans. JSASS Aerospace Tech. Japan 9 1 - 8 2011年04月

A Research on Mitigation Method Against Secondary Arcing on Solar Array 査読有り

Tomohiro Wada,Hirokazu Masui,Kazuhiro Toyoda,Mecgu Cho

The Japan Society for Aeronautical and Space Sciences 2011年04月

Initial Operations of Center for Nanosatellite Testing 査読有り

Mengu Cho,Hirokazu Masui,Yasuhiro Akahoshi,Koju Hiraki,Minoru Iwata,Kazuhiro Toyoda,Shinji Hatta

2nd Nano-Satellite Symposium 2011年03月

Development of Thruster using Electric Arc in Plasma Environment for Nano-Satellite 査読有り

Masayoshi Nakamoto,Kazuhiro Toyoda,Mengu Cho

2nd Nano-Satellite Symposium 2011年03月

Development of High Voltage Technology Demonstration Satellite, HORYU-2 査読有り

Hiroki Nishimura,Mengu Cho

2nd Nano-Satellite Symposium 2011年03月

Development of Ground Operation Software for Nano-Satellite HORYU 査読有り

Daiki kubo,Mengu Cho

2nd Nano-Satellite Symposium 2011年03月

Announcing the IEEE Transactions on Plasma Science Special Issue on Spacecraft Charging Technology January 2012

Lai S., Cooke D., Payan D., Hilgers A., Cho M., Garrett H., Ferguson D., Roussel J., Wheelock A.

IEEE Transactions on Plasma Science ( IEEE Transactions on Plasma Science ) 39 ( 1 PART 2 ) 2011年01月

Characterization of solar cell degradation due to electrostatic discharge on multi-junction solar cell 査読有り

Okumura T., Imaizumi M., Toyoda K., Cho M.

Conference Record of the IEEE Photovoltaic Specialists Conference 2599 - 2603 2010年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

A shunt resistance on the solar cell edge which is made by an electrostatic discharge (discharge) causes the degradation of multi-junction solar cell (MJ cell). To prevent the degradation, a trench was formed along the edge of multi-junction solar cell (AD MJ cell). The degradation characterization tests were performed on state-of art MJ cell and AD MJ cell to investigate the effect of trench in plasma environment. © 2010 IEEE.

DOI： 10.1109/PVSC.2010.5614144

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Electrostatic discharge test with simulated coverglass flashover for multi-junction GaAs/Ge solar array design 査読有り

Hoang B., Wong F., Funderburk V., Cho M., Toyoda K., Masui H.

Conference Record of the IEEE Photovoltaic Specialists Conference 1118 - 1123 2010年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Space Systems/Loral (SS/L) successfully completed electrostatic discharge (ESD) tests of Multi-junction (MJ) GaAs/Ge solar array design in geosynchronous space environment. This ESD test was based on ISO-11221, Space systems - Space solar panels -Spacecraft Charging Induced Electrostatic Discharge Test Methods. In addition to the ISO reference for the test schematic, SS/L implemented modified test circuitry to better simulate the on-orbit operational conditions of our solar array design. The ESD test circuit also included simulated solar array panel coverglass flashover. The ESD test program utilized a 25-cell coupon that had been subjected to 2,000 thermal cycles caused by earth eclipses in GEO orbit and > 12,000 thermal cycles caused by the shadow of the spacecraft antennas. Other ESD test coupons are 4-cell coupons that, after baseline ESD experiments, can later be subjected to combined space environmental exposures tests. To demonstrate design robustness, we performed ESD tests to voltages and currents that are higher than that of on-orbit solar array operational voltages and currents. This paper discusses the coverglass flashover simulation, ESD test setup, the importance of the electrical test design in simulating the on-orbit operational conditions, and the test results. © 2010 IEEE.

DOI： 10.1109/PVSC.2010.5614721

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Development of Electron-Emitting Film for Spacecraft Charging Mitigation: Environment exposure tests 査読有り

Khan A., Sumida T., Iwata M., Toyoda K., Cho M., Fujita T.

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition 2010年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Prevention of spacecraft charging and discharging has become increasingly important as GEO satellites employ higher bus voltage. There are numerous mitigation techniques against spacecraft charging including electron emission from the spacecraft chassis. A new electron emission device operating in completely passive manner has been developed which utilizes the field enhancement at the triple junction formed at the interface of metal and insulator exposed to space. It is named as Electron Emitting Film for Spacecraft Charging Mitigation (ELF's CHARM). Micro-etching was applied to polyimide-copper (PI-Cu) laminated film to manufacture a laboratory prototype. ELF utilizes pre-breakdown electron emission current leading to arcing at the triple junction keeping the current at the steady state. The electric field at the triple junction is macroscopically enhanced by charging of the polyimide film and microscopically by dielectric impurity on the copper surface. Theoretical rough estimate gives a current of 100 to 1,000μA. The laboratory experiment confirmed stable current emission from 10 to 100 μA from a sample of several centimeters square for 4 hours. Its robustness against ground handling and in-orbit contamination has already been demonstrated. To prepare for flight demonstration as early as 2011, the research and development have been accelerated. To ensure the endurance, recently 100 accumulated hours emission test and effect of high energy electron and proton and thermal cycling have been investigated on recently developed ELF. Post-emission of this electron emitting film confirms the durability under those harsh environments. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

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Preliminary experiments for establishing an ESD ground testing method of solar array 査読有り

Toyoda K., Wada T., Yoke T., Suzuki T., Masui H., Cho M.

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition 2010年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

ESD ground testing on satellite solar array paddle is performed to mitigate catastrophic accidents. An international standard is desired to perform international satellite business smoothly. A standard has been developed in laboratory of spacecraft environment interactions. The draft has been applied. In this paper, preliminary experiments were performed to improve the testing method. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

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Understanding the effect of atomic oxygen exposure on surface and volume resistivity change in LEO 査読有り

Mundari N., Khan A., Iwata M., Toyoda K., Cho M.

61st International Astronautical Congress 2010, IAC 2010 12 10018 - 10026 2010年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Spacecraft surface charging can leads to arcing and a loss of electricity generation capability of solar panel or even loss of a satellite. The arcing problem may be further aggravated by the atomic oxygen (AO) exposure in Low Earth orbit, which modify the surface of materials like polyimide, Teflon, anti reflective coating, cover glass etc used on satellite surface affecting materials properties such as resistivity, secondary electron emissivity, photo electron emission which govern the charging behavior. These properties are crucial inputs parameters for spacecraft charging analysis. To study the AO exposure effect on the charging governing properties, an AO exposure facility based on laser detonation of oxygen was built which produce 8-14km atomic oxygen with higher flux than in orbit. After exposing materials to 10years equivalent AO flux at the altitude of 700-800km, surface charging properties like resistivity and secondary electron emission is being measured. Measurement of surface and volume resistivity for AO exposed samples was done for polyimide. The measurement was done using the charge storage decay method at a room temperature, which is considered most appropriate for measuring the resistivity for space application. It was found that the value of surface resistivity increases more than two fold and volume resistivity remains same. Measurement of secondary electron emission characteristics is under progress.

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Development and verification of on-orbit demonstration device for Electron-emitting Film (ELF) for spacecraft charging mitigation 査読有り

Sumida T., Shibagaki R., Khan A., Iwata M., Toyoda K., Tomonari S., Cho M.

61st International Astronautical Congress 2010, IAC 2010 12 10011 - 10017 2010年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

As geo-stationary (GEO) satellite bus voltage increased due to the increased size of the satellites, the number of solar array failures due to spacecraft charging increased. We are developing an electron emitter that emits electrons from the conductor by using the enhanced electric field at the triple junction which occurs simultaneously while spacecraft charging. The emitter is composed of an insulator on top of cupper plate. Parts of the cupper plate are exposed through the insulator ensuring the triple junctions that are the source of electron emission. This emitter operates in a completely passive fashion. In this paper, the authors conducted the verification test of this emitter after making a measurement circuitry. This time, the surfaces of the emitters were coated with a special material to enhance the electron emission current. In the ground test, the emitters were biased to a highly negative potential with respect to a vacuum chamber ground and exposed to an electron beam. This leaded the simulation of satellite charging. Then the operation of the measurement system had been checked to confirm the emission as well as surface potential. These results permit this electron emitter to be used in actual space environment.

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Capacity building in basic space technology development through on-the-job training in nano-satellite design, building and testing 査読有り

Cho M., Balogh W.

61st International Astronautical Congress 2010, IAC 2010 2 1710 - 1716 2010年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Developing countries that in the past have mostly focused on applications-oriented aspects of space technology are increasingly also interested in building indigenous capacities for basic space technology development. A nano-satellite development program is an ideal first-step to establish such a basic capacity. Experience gained through on-the-job training, going through the complete cycle of designing, building and testing a satellite, is crucial to gain this capacity. To fill that demand there is a need for educational institutions to offer appropriate on-the-job training opportunities. Kyushu Institute of Technology and the United Nations Office for Outer Space Affairs will launch a long-term fellowship programme on nano-satellite technologies for post-graduate level students from developing countries and countries with economies in transition. The first students supported by the fellowship programme are expected to enrol in Kyushu Institute of Technology on October 1st, 2011. The length of the fellowship programme for each student is three years. Students will work in the newly established Centre for Nanosatellite Testing, which can handle a full range of environmental tests required for a 50cm-class nano-satellite. Because all tests can be conducted with the facilities available inside the campus, intensive and efficient cycles of designing, building and testing become possible. This paper describes the details of the fellowship program. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

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Characterization experiments of secondary arcs on solar arrays: Threshold and duration 査読有り

Masui H., Ose T., Kitamura T., Toyoda K., Cho M.

Journal of Spacecraft and Rockets 47 ( 6 ) 966 - 973 2010年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

An electrostatic discharge test performed on a solar array panel is one of the important tests carried out before spacecraft launch to ensure spacecraft reliability in orbit. In this study, the effects of secondary arcs on the solar array, which can cause catastrophic accidents, are considered. The sustained-arc threshold of multijunction and silicon solar arrays was investigated to establish the design guidelines for ensuring the safety of satellite solar arrays. In this experimental study, the string voltage, string current, gap length, and solar-cell type were selected as test parameters. Gap lengths were 0.5, 0.8, 1.0, and 2.0 mm. For 0.5 and 0.8mmof gap length, a permanent sustained arc occurred under the condition of 1.5 A of string current for 50, 70, 90, and 110 V of string voltage. Furthermore, temporary sustained-arc duration exponentially increased with increasing string current. Temporary sustained-arc duration longer than 1 ms can serve as a practical alarm for the imminent permanent sustained-arc inception. © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

DOI： 10.2514/1.49571

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