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OSCAR IV (aka OSCAR 4) is the fourth amateur radio satellite launched by Project OSCAR and the first targeted for Geostationary orbit on 12 December 1965. The satellite was launched piggyback with three United States Air Force satellites on a Titan IIIC launch vehicle. The satellite was regular tetrahedron, 48 cm on each side. It had four independent monopole antennas and like OSCAR 3 contained a tracking beacon transmitter and a communications repeater. It was powered by a solar cell array and batteries. The launch vehicle suffered a partial failure and placed OSCAR IV in an unplanned 161 km × 33000-km orbit preventing the planned coverage. OSCAR IV was built by the TRW Radio Club of Redondo Beach, California. It had a 3 Watt 10 kHz wide linear transponder (144 MHz uplink and 432 MHz downlink). The satellite remained in operation for 85 days, until March 16, 1966. The satellite eventually re-entered Earth's atmosphere on April 12, 1976. Only 12 two-way communications were established through the linear transponder, but one on December 22, 1965 was the first direct satellite communication between the United States and the USSR. ==Project OSCAR== Project OSCAR Inc. started in 1960 with the TRW Radio Club of Redondo Beach, California and radio amateurs who worked at TRW and other California defense companies, to investigate the possibility of putting an amateur satellite in orbit. Project OSCAR was responsible for the construction of the first Amateur Radio Satellite OSCAR-1, that was successfully launched from Vandenberg AFB in California . OSCAR 1 orbited the earth for 22 days, transmitting the “HI” greeting you see in Morse Code above. Project OSCAR was responsible for launching of 3 other amateur radio satellites during the 1960s: OSCAR 1, OSCAR 2, and OSCAR 3. In 1969, AMSAT-NA was founded by radio amateurs working at NASA's Goddard Space Flight Center and the Baltimore-Washington DC region, to continue the efforts begun by Project OSCAR. Its first project was to coordinate the launch of Australis-OSCAR 5, constructed by students at the University of Melbourne.〔(【引用サイトリンク】 title=Space Satellites from the World's Garage – The Story of AMSAT )〕 Today, over fifty years later, Project OSCAR still exists as part of the San Jose (CA) Amateur Radio Club. Its mission is “To initiate and support activities that promote the Satellite Amateur Radio Hobby”. The primary goal is to reach out and provide logistical support, training and in some cases equipment to amateur radio associations, schools and the public at large. 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「OSCAR 4」の詳細全文を読む スポンサード リンク
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