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The Quasi-Zenith Satellite System (QZSS), is a proposed three-satellite regional time transfer system and Satellite Based Augmentation System for the Global Positioning System, that would be receivable within Japan. The first satellite 'Michibiki' was launched on 11 September 2010.〔(【引用サイトリンク】title=Launch Result of the First Quasi-Zenith Satellite 'MICHIBIKI' by H-IIA Launch Vehicle No. 18 )〕 Full operational status was expected by 2013. In March 2013, Japan's Cabinet Office announced the expansion of the Quasi-Zenith Satellite System from three satellites to four. The $526 million contract with Mitsubishi Electric for the construction of three satellites is slated for launch before the end of 2017.〔http://www.spaceflightnow.com/news/n1304/04qzss/ Japan to build fleet of navigation satellites 2013-04-04 Retrieved 2013-04-05〕 Authorized by the Japanese government in 2002, work on a concept for a Quasi-Zenith Satellite System (QZSS), or in Japanese, began development by the Advanced Space Business Corporation (ASBC) team, including Mitsubishi Electric, Hitachi, and GNSS Technologies Inc. However, ASBC collapsed in 2007. The work was taken over by the Satellite Positioning Research and Application Center. SPAC is owned by four departments of the Japanese government: the Ministry of Education, Culture, Sports, Science and Technology, the Ministry of Internal Affairs and Communications, the Ministry of Economy, Trade and Industry, and the Ministry of Land, Infrastructure and Transport.〔(【引用サイトリンク】title=Service Status of QZSS )〕 QZSS is targeted at mobile applications, to provide communications-based services (video, audio, and data) and positioning information. With regards to its positioning service, QZSS can only provide limited accuracy on its own and is not currently required in its specifications to work in a stand-alone mode. As such, it is viewed as a GNSS Augmentation service. Its positioning service could also collaborate with the geostationary satellites in Japan's Multi-Functional Transport Satellite (MTSAT), currently under development, which itself is a Satellite Based Augmentation System similar to the U.S. Federal Aviation Administration's Wide Area Augmentation System (WAAS). ==Orbit== QZSS uses three satellites, each 120° apart, in highly inclined, slightly elliptical, geosynchronous orbits. Because of this inclination, they are not geostationary; they do not remain in the same place in the sky. Instead, their ground traces are asymmetrical figure-8 patterns (analemmas), designed to ensure that one is almost directly overhead (elevation 60° or more) over Japan at all times. The nominal orbital elements are: 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Quasi-Zenith Satellite System」の詳細全文を読む スポンサード リンク
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