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第18回宇宙科学シンポジウム (2018年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 18th Space Science Symposium (January 9-10, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000118129, レポート番号: P-096

第25回アストロダイナミクスシンポジウム (2015年7月27-28日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, The 25th Workshop on JAXA Astrodynamics and Flight Mechanics 2015 (July 27-28, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000054053, レポート番号: C-10

第25回アストロダイナミクスシンポジウム (2015年7月27-28日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, The 25th Workshop on JAXA Astrodynamics and Flight Mechanics 2015 (July 27-28, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000054043, レポート番号: B-21

In recent years, as practical applications of microsatellites spread, missions of them have become advanced and it has been required that the development of them is short-term and low-cost. In order to achieve these requirements, two points of improvement, such as reliability of software due to high re-usability and flexible reconfiguration capability on orbit, are important in terms of onboard software. The conventional development of on-board software for microsatellites has been performed individually each satellite, and software which can achieve the two points mentioned above has not been developed. Therefore, as a framework to develop on-board software for microsatellites that satisfies high re-usability and flexible reconfiguration capability, the software architecture named "Command Centric Architecture (C2A)" was proposed as a doctoral dissertation at The University of Tokyo. This software architecture has three characteristics: describing common functions among every spacecraft as commands and functions associated with them, modularizing unique functions for each satellite, and coupling common functions with unique functions via definition tables. With these features, the onboard software realizes the flexible reconfiguration capability of itself, which is the middle of the parameter change and the memory rewrite from a viewpoint of the load for implementation, the risk of reconfiguration and the ability to deal with anomalies. Furthermore, this software framework separates functions common to spacecraft and spacecraft-specific functions and narrows hardware-dependent parts by modularizing spacecraft-specific functions. Thanks to them, it is possible to reuse many parts of the software in different spacecraft. C2A was applied to some Earth-orbiting microsatellites, UNIFORM, Hodoyoshi-3 and 4, and it was refined. After that, it was applied to PROCYON which is the first interplanetary micro-spacecraft. Porting C2A to PROCYON was quite easy because these four spacecraft use the same model of onboard computer. By using C2A on its onboard software, development of the software was completed in only about 5.5 months. Also, we were able to deal with various events by utilizing C2A's flexible reconfiguration capability during operation of PROCYON. In addition, we have completed implementation of C2A to the onboard software of EQUULEUS, which is 6U CubeSat currently under development. C2A porting from PROCYON to EQUULEUS was realized in a very short time in spite of EQUULEUS using a different model of onboard computer. In this way, C2A has various advantages such as shortening development period of small spacecraft, improving the reliability of onboard software, the flexibility of operation, therefore it gives a great advantage to the mission using the small spacecraft.

第17回宇宙科学シンポジウム (2017年1月5日-6日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 17th Space Science Symposium (January 5-6, 2017. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 42名, 資料番号: SA6000060054, レポート番号: P-012

第17回宇宙科学シンポジウム (2017年1月5日-6日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 17th Space Science Symposium (January 5-6, 2017. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 22名, 資料番号: SA6000060056, レポート番号: P-014

This paper presents the development and initial operation results of 50kg-class deep space exploration micro-spacecraft PROCYON (Proximate Object Close flYby with Optical Navigation), which was jointly developed by the University of Tokyo and Japan Aerospace Exploration Agency (JAXA). The primary mission of PROCYON is the demonstration of 50kg-class deep space exploration bus system including the demonstration of high-efficiency GaN-based SSPA (Solid State Power Amplifier) for communication and high-precision navigation by a novel DDOR (Delta Differential One-way Range) observation method. PROCYON also has some secondary advanced missions, which are deep space flight to a Near-earth asteroid and high resolution observation of the asteroid during close and fast flyby, and the wide view scientific observation of geocorona by a Lyman alpha imager from a vantage point outside of the geocoronal distribution. PROCYON was developed with very low cost (a few million dollars) and within very short period (about 1 year), taking advantage of the heritage from Japanese Earth-orbiting micro satellite missions. PROCYON was launched into an Earth departure trajectory together with Japanese second asteroid sample return spacecraft Hayabusa-2 on December 3, 2014, and it has achieved its primary mission and some of the secondary missions.

In recent years, low cost and quick development of very small satellites ranging from CubeSats of 1 kg to micro-satellites of approximately 50 kg have allowed advances in space development and application. Although most of these satellites are in Earth orbits, a small spacecraft for deep-space missions has been developed and launched for the first time in the world. The Proximate Object Close Flyby with Optical Navigation (PROCYON) micro-interplanetary spacecraft, developed by the University of Tokyo and the Japan Aerospace Exploration Agency, was launched in December 2014 as one of the secondary payloads of the asteroid sample return spacecraft "Hayabusa-2." The main mission of PROCYON is to demonstrate critical technologies of 50-kg-class interplanetary spacecraft exploration such as communication, attitude control, thermal control, and power generation. Furthermore, advanced missions of PROCYON enable a close flyby of an asteroid at an altitude of approximately several dozen kilometers and the capture of high-resolution images of approximately several meters per pixel by a telescope. In the flyby missions, the change of the target direction vector from the spacecraft to the asteroid is steeper than that of past flyby interplanetary probes. Thus, the spacecraft could not keep the asteroid in a telescope's field of view only by performing an attitude maneuver of the entire body. To overcome this attitude maneuverability problem, a small and line-of-sight controllable telescope using a rotating mirror was developed and implemented on PROCYON. Due to the system constraint of the micro-spacecraft, this telescope should also be used for optical navigation by the faint asteroid images performed before several days of closest approach. The telescope is very lightweight, approximately 680 g. Moreover, its exposure time range is very high; thus, it can capture images of very dark astronomical bodies of approximately 12 magnitudes to supply information for trajectory correction maneuvers as well as bright bodies observed at a short distance during the close flyby. The results of experiments in the interplanetary orbit are shown in the presentation. Several 12 magnitude stars were identified from the images captured in orbit by utilizing the noise reduction techniques. This result complies with mission requirement of the optical navigation of PROCYON to extract the target images at least three days before closest approach. During the Earth approaching period, a visual feedback tracking experiment was performed utilizing the reflected light from the Earth. Time history of the rotation angle of the telescope shows the direction determination accuracy of the target body by the luminance center extraction using on-board image processing system. The know-how of the optical system of PROCYON enables a variety of missions in the interplanetary field performed by micro-spacecraft.

第16回宇宙科学シンポジウム (2016年1月6日-7日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 16th Space Science Symposium (January 6-7, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 13名, 資料番号: SA6000046129, レポート番号: P-130

第16回宇宙科学シンポジウム (2016年1月6日-7日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 16th Space Science Symposium (January 6-7, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 11名, 資料番号: SA6000046052, レポート番号: P-053

This paper presents the development and initial operation results of 50kg-class deep space exploration microspacecraft PROCYON (Proximate Object Close flYby with Optical Navigation), which was jointly developed by the University of Tokyo and Japan Aerospace Exploration Agency (JAXA). The primary mission of PROCYON is the world’s first demonstration of 50kg-class deep space exploration bus system which includes the demonstration of high-efficiency GaN-based SSPA (Solid State Power Amplifier) for communication and high-precision navigation by a novel method of DDOR (Delta Differential One-way Range) observation. PROCYON also has some secondary advanced missions, which are deep space flight to a Near-earth asteroid and high resolution observation of the asteroid during close and fast flyby, and the wide view scientific observation of geocorona by a Lyman alpha imager from a vantage point outside of the Earth’s geocoronal distribution. PROCYON was developed at very low cost (a few million dollars) and within very short period (about 1 year), taking advantage of the heritage from Japanese Earth-orbiting micro satellite missions. PROCYON was launched into an Earth departure trajectory together with Japanese second asteroid sample return spacecraft Hayabusa-2 on December 3, 2014, and it has achieved its primary mission and some of the secondary missions.

第15回宇宙科学シンポジウム (2015年1月6日-7日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 15th Space Science Symposium (January 6-7, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000034246, レポート番号: P-247

第15回宇宙科学シンポジウム (2015年1月6日-7日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 15th Space Science Symposium (January 6-7, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000034121, レポート番号: P-121

第14回宇宙科学シンポジウム (2014年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 14ｔh Space Science Symposium (January 9-10, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 17名, 資料番号: SA6000058012, レポート番号: S2-004

第14回宇宙科学シンポジウム (2014年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 14ｔh Space Science Symposium (January 9-10, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000058095, レポート番号: P2-063