研究者詳細 - 趙　孟佑

論文 - 趙　孟佑

分割表示643 件中 181 - 200 件目／全件表示 >>

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

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85016030168&origin=inward

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

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85016053161&origin=inward

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

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85019752838&origin=inward

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