Hodoyoshi-1 (Remote Sensing Microsatellite)
In 2010, the University of Tokyo started the research and development initiative “New Paradigm Space Development and Utilization Opened by Micro- Nanosatellites - introducing the 'Reasonably Reliable Systems' (Hodoyoshi in Japanese) concept.” Funding is provided by JSPS (Japan Society for the Promotion of Science) in the FIRST (Funding Program for World-Leading Innovative R&D on Science and Technology) program , initiated by CSTP (Council for Science and Technology Policy) of Cabinet Office, Government of Japan. 1)
The project aims to accelerate the technology development and practical utilization of micro/nano-satellites. Micro/nano-satellites are expected to reduce the cost of satellite development by an order(s) of magnitude which may in turn open new ways of satellite utilization by the introduction of satellite constellations. The following research goals are to be pursued in the project period of 2010-2015 through collaboration of several leading universities and small industries in Japan.
1) Conceptualization and demonstration of novel reliability concept "Reasonable Reliable Systems ("Hodoyoshi" in Japanese)" suitable for micro/nano-satellites.
2) Research and development of all the required components for micro/nanosatellites with advanced concept and technologies, aiming for the world top level "performance per size".
3) Innovation of satellite development process including standardization of interfaces and software, ways of ground test, etc, to further reduce the development cost and period.
4) Construction of all-Japan consortium for R&D, supply chain network, creation of international user communities, and capacity building.
As part of the Hodoyoshi project, four micro/nanosatellites are under development and Hodoyoshi-1, the first one, has been designed and developed by AxelSpace Corporation of Kashiwa City, Japan. 2) 3) 4) 5) 6)
The four satellites to be developed by Japanese institutions are:
• Hodoyoshi-1 :The University of Tokyo and NESTRA (Next Generation Space System Technology Association)
• ChubuSat-1 : Nagoya University and Daido University
• Tsubame : Tokyo Institute of Technology, Tokyo University of Science and JAXA
• QSAT-EOS : Kyushu University.
Figure 1: Photo of the HodoYoshi-1 microsatellite (image credit: Axelspace)
Hodoyoshi-1 is a microsatellite with the aim to provide fairly high-resolution imagery of Earth's surface. The spacecraft cubic structure has a size of 60 cm on a side, the mass of the spacecraft is ~60 kg and the average power is ~50 W. The satellite is equipped with an onboard computer (FPGA), a reaction wheel, a star sensor, a MEMS gyro, a GPS receiver, thrusters, and an optical sensor. The satellite is capable of accurate 3-axis attitude control and orbital control using hydrogen peroxide water thrusters.
Figure 2: Illustration of the Hodoyoshi-1 microsatellite (image credit: University of Tokyo)
RF communications: Payload data communications in X-band at data rates of 10-20 Mbit/s.
JAXA developed a novel communications system for 320 Mbit/s downlink with 16 QAM for small satellites in the 50 kg class. 11)
Figure 3: Young engineers with their Hodoyoshi-1 microsatellite (image credit: Axelspace)
Launch: A launch of Hodoyoshi-1 as a secondary payload is scheduled for August 2014 on a Dnepr-1 vehicle from the Yasny Cosmodrome, Russia. The primary payload on this flight is the ASNARO minisatellite of USEF, Japan.
Orbit: Sun-synchronous orbit, altitude of 504 km, inclination = 97.4º, LTDN (Local Time on Descending Node) = 11:00 hours.
The secondary payloads on this mission are:
• QSat-EOS, a microsatellite (<50 kg) Kyushu University (KU), Fukuoka, Japan.
• Hodoyoshi-1, a microsatellite (60 kg) of the University of Tokyo and NESTRA (Next Generation Space System Technology Association)
• Tsubame, a microsatellite (~48 kg) of Tokyo Institute of Technology, Tokyo University of Science and JAXA
• ChubuSat-1, a microsatellite (~ 50 kg) of Nagoya University and Daido University, Japan.
Sensor complement: (Camera)
The satellite will observe the Earth using an optical pushbroom imager (line scanner) with a GSD (Ground Sample Distance) of 6.7 m on a swath width of ~28 km. The camera was developed by Genesia Corporation, Tokyo, Japan. The design employs a refractive telescope and lenses providing a wide field of view.
Figure 4: Photo of the pushbroom imager (image credit: Axelspace)
Table 1: Specification of the camera system
The medium-resolution imagery is expected to be used in a wide range of applications including agriculture, forestry, fishery, map-making, GIS (geographic information system) and disaster monitoring.
1) Shinichi Nakasuka,“The University of Tokyo FIRST Program,” Sept. 30, 2011, URL: http://www.u-tokyo.ac.jp/first/summary/smry-nakasuka_e.html
2) Shinichi Nakasuka, Rei Kawashima, “Micro/Nano-satellite Activities by Japanese Universities and Vision towards International Contribution,” Proceedings of UN COPUOS (Committee on the Peaceful Uses of Outer Space), UNOOSA, Vienna, Austria, June 6-15, 2012, URL: http://www.oosa.unvienna.org/pdf/pres/copuos2012/tech-23.pdf
3) Tokyo University, May 16, 2012, URL: http://www.t.u-tokyo.ac.jp/etpage/release/2012/2012051601.html
4) Hiroyuki Koizumi, Junichi Aoyama, Koji Yamaguchi, “Engineering Model Development of a Miniature Ion Propulsion System,” Proceedings of the UN/Japan Workshop and The 4th Nanosatellite Symposium (NSS), Nagoya, Japan, Oct. 10-13, 2012, paper: NSS-04-0125
5) Shinichi Nakasuka, “Opening Remarks at the 4th Nano-satellite Symposium,” Proceedings of the UN/Japan Workshop and The 4th Nanosatellite Symposium (NSS), Nagoya, Japan, Oct. 10-13, 2012, URL: http://www.nanosat.jp/4th/pdf/Day1-1_OpeningSession1_Nakasuka/Opeining_Prof.Nakasuka.pdf
6) Hironori Sahara, “Systems Engineering for Microsatellite,” 6th International Workshop on Remote Sensing and Environmental Innovations in Mongolia, June 10-11, 2013, URL: http://spe.num.edu.mn/6th-rsconf/WS-presentation/Hironori_Sahara.pdf
9) “Micro-Satellite for Earth Remote Sensing, Hodoyoshi-1, Axelspace, Jan. , 2014, URL: http://www.axelspace.com/wp-content/docs/Hodoyoshi-1_Flyer_EN.pdf
10) Shinichi Nakasuka, “Current Status and Future Vision of Hodoyoshi Microsatellites – Systems for Quick and Affordable Space Utilizations,” 2013, URL: http://www.nanosat.jp/images/report/pdf/nanosat_201311.pdf
11) Hirobumi Saito, Naohiko Iwakiri , Atsushi Tomiki, Takahide Mizuno, Hiromi Watanabe, Tomoya Fukami, Osamu Shigeta, Hitoshi Nunomura, Yasuaki Kanda , Kaname Kojima, Takahiro Shinke, Toshiki Kumazawa, “High-Speed Downlink Communications with Hundreds Mbps from 50kg Class Small Satellites,” Proceedings of the 63rd IAC (International Astronautical Congress), Naples, Italy, Oct. 1-5, 2012, paper: IAC-12-B2.3.1
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.