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Commentary−146−Synthesiology - English edition Vol.11 No.3 pp.146–157 (Feb. 2017) The X-ray astronomy satellite “ASTRO-H (Hitomi)” dramatically improved functions and performances required for satellite systems compared with conventional Japanese satellites.[2]–[5] Development of equipment onboard ASTRO-H was conducted under wide-ranging international cooperation. Therefore, development that ensured continuation of the conventional development as well as compliance to international standard was required. The SpaceWire international standard[6][7] employed for ASTRO-H was a de jure standard that the European Space Agency (ESA) oversaw. We were able to incorporate proprietary standards that were formed with Japanese scientic satellites over the years into the international standard.Looking back at the process by which Japanese proprietary standards were incorporated into the SpaceWire international standard and considering the success factors, it is possible to provide explanation based on the way of thinking presented in Reference [8]. The SpaceWire international standard was consolidated and established through discussions among the parties involved about the functions and performances to be realized, and its implementation method was set by specifying as international standards while technological development was conducted. This can be called a development-type standard.[9] In this article, we look back on the proposal activities based on the thoughts of Reference [8], and discuss the reproducible proposal process for the development-type international standard of which cases are increasing recently. Chapter 2 explains the route by which the system architecture of ASTRO-H, which is a compilation of SpaceWire standard products totally adopted for the first time, was recognized internationally. Chapter 3 summarizes the technological factors that allowed the Japanese proprietary technologies 1 IntroductionThe onboard equipment installed in satellites is mutually connected by networks, and they transmit and receive commands and monitor signals called telemetry from each other. Standards for transmitting such signals are closely related to the ground stations that remotely control satellites and manage overall satellite systems. Since operating facilities of ground stations of various countries are used mutually, there is a growing demand for network communication standards to comply with international standards.The process of introducing such international standards to Japan generally involves surveying several existing standards including for consumer products as well as spacecrafts, trading off with those standards, and selecting the specification that fullls the required function and performance and for which continuity can be expected, after checking the background situation of standard establishment. On the other hand, in Japan, since proprietary development has been conducted for satellites used in scientific observations from the beginning, there are cases in which proprietary standards are being used.[1] For international standards, continuous revisions are conducted reflecting progress in technology, and this also involves revisions based on rapid technological advances in consumer product markets as well as establishment of new standards. While it should be possible to incorporate Japanese proprietary standards into international standards, this was not easy. This was not because of technological factors but because there seemed to be no motivation for proposing the Japanese proprietary standards as international standards for communication among the equipment onboard satellites.—Successful factors for the development of a de jure standard—Incorporating standards for spacecraft in Japan involves trading off various existing standards to comply with requirements and sustainability. However, well-established proprietary specifications developed for Japanese scientific satellites were successfully incorporated into the international standard of embedded networks, called SpaceWire, which was adopted for the X-ray astronomical satellite “ASTRO-H (Hitomi).” Looking back on this proposal process, we studied a mutual collaboration scheme to incorporate Japan’s proposal, regarding the development type international standards.Contributing to the SpaceWire international standard Keywords : De-jure standard, de-facto standard, SpaceWire, international standardization [Translation from Synthesiology, Vol.11, No.3, p.148–158 (2018)]Hiroki HIHARA1*, Masaharu NOMACHI2 and Tadayuki TAKAHASHI31.On-board Electronics Department, Space Engineering Division, NEC Space Technologies 1-10 Nisshin-cho, Fuchu 183-8551, Japan *E-mail: , 2. Osaka University 1-1 Machikaneyama, Toyonaka 560-0043, Japan, 3. KavliInstitute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa 277-8583, Japan Original manuscript received March 2, 2018, Revisions received July 20, 2018, Accepted July 23, 2018

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