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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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. 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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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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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. 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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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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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, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This paper describes the algorithm development of Arcsecond Pico Star Tracker (APST) at Seoul National University. The pico star tracker is developed using COTS because it’s affordable, and less development time. But COTS component decreases the overall performance. In APST, the lens distortion increases the measurement error which causes misidentification of stars and higher processing time for star identification. To overcome this, the relative star selection algorithm is developed which selects the stars with less measurement error and it’s compared with conventional bright star selection method. The selection algorithm is tested with 75-star constellation in the simulator and it has delivered 100% success rate and accuracy of 71 arcseconds in boresight with average processing time of 22 ms. Whereas the conventional bright star selection delivered low success rate of 28% because it selects the stars only based on brightness and processing time increases as a number of stars in the FOV increases. Hence the relative star selection algorithm is efficient for APST.

DOI： 10.2514/6.2018-2199

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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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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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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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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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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 The Japan Society for Aeronautical and Space Sciences. The second-generation star tracker estimates pointing knowledge of a satellite without a-priori knowledge. But star trackers are larger in size, heavier, power hungry and expensive for nanosatellite missions. The Arcsecond Pico Star Tracker (APST) is designed based on the limitations of nanosatellites and estimated to provide pointing knowledge in an arcsecond. The APST will be used on the SNUSAT-2, Earth-observing nanosatellite. This paper describes the requirements of APST, trade-off for the selection of image sensor, optics, and baffle design. In addition, a survey of algorithms for star trackers and a comparison of the specifications of APST with other Pico star trackers are detailed. The field of view (FOV) estimation shows that 17° and 22° are suitable for APST and this reduces stray light problems. To achieve the 100% sky coverage, the FOV of 17° and 22° should able to detect the 5.85 and 5.35 visual magnitude of stars, respectively. It is validated by estimating the signal to noise ratio of APST and night sky test results. The maximum earth stray light angle is estimated to be 68° and a miniaturized baffle is designed with the exclusion angle of 27°.

DOI： 10.2322/tjsass.60.355

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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.

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