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KH-9 (BYEMAN codename HEXAGON), commonly known as Big Bird〔p.32 Big Bird〕 or Keyhole-9, was a series of photographic reconnaissance satellites launched by the United States between 1971 and 1986. Of twenty launch attempts by the National Reconnaissance Office, all but one〔http://www.youtube.com/watch?v=XXBl03wVHOY〕 were successful. Photographic film aboard Big Bird was sent back to Earth in recoverable film return capsules for processing and interpretation. The best ground resolution achieved by the main cameras was better than 0.6 meters.〔 They are also officially known as the Broad Coverage Photo Reconnaissance satellites (Code 467), built by Lockheed Corporation for the National Reconnaissance Office.〔 The KH-9 was declassified in September 2011 and an example was put on public display,〔https://fas.org/blogs/secrecy/2011/09/nro_50th/〕〔http://www.space.com/12996-secret-spy-satellites-declassified-nro.html〕 for one day, on September 17, 2011, in the parking lot of the Steven F. Udvar-Hazy Center of the National Air and Space Museum, outside Dulles International Airport.〔Doyle, John M., Big Bird, uncaged, Air and Space, December 2011/January 2012, p.10〕〔(Mail Online: ''Top secret surveillance satellite Big Bird, which took pictures of Soviet Union during Cold War, goes on public viewing'' ), By Laurie Whitwell UPDATED: 16:33 EST, 17 September 2011〕 On January 26, 2012 the National Museum of the United States Air Force put a KH-9 on public display along with its predecessors the KH-7 and KH-8.〔Cohen, Aubrey, ("Three former spy satellites go on display" ), ''Seattle Post-Intelligencer'', Thursday, January 26, 2012〕 ==Development== The KH-9 was originally conceived in the early 1960s as a replacement for the Corona search satellites. The goal was to search large areas of the earth with a medium resolution camera. The KH-9 carried two main cameras, although a mapping camera was also carried on several missions. The photographic film from the cameras was sent to recoverable re-entry vehicles and returned to Earth, where the capsules were caught in mid-air by an aircraft. Four re-entry vehicles were carried on most missions, with a fifth added for missions that included a mapping camera. Between September 1966 and July 1967, the contractors for the Hexagon subsystems were selected. LMSC was awarded the contract for the Satellite Basic Assembly (SBA), Perkin Elmer for the primary Sensor Subsystem (SS), McDonnell for the Reentry Vehicle (RV), RCA Astro-Electronics Division for the Film Take Up system, and Itek for the Stellar Index camera (SI). Integration and ground-testing of Satellite Vehicle 1 (SV-1) was completed in May 1971, and it was subsequently shipped to Vandenberg Air Force Base in a 70 ft container. Ultimately, four generations ("blocks") of KH-9 Hexagon reconnaissance satellites were developed. KH9-7 (1207) was the first to fly a Block-II panoramic camera and SBA. Block-III (vehicles 13 to 18) included upgrades to electrical distribution and batteries. Two added tanks with ullage control for the Orbit Adjust System (OAS) and new thrusters for the Reaction Control System (RCS) served to increase KH-9's operational lifetime. In addition the nitrogen supply for the film transport system and the camera vessel was increased. Block-IV was equipped with an extended command system using plated wire memory.〔 In the mid 1970s, over 1000 people in the Danbury, Connecticut area worked on the secret project.〔Decades Later, a Cold War Secret Is Revealed Published December 25, 2011 | Associated Press http://www.foxnews.com/us/2011/12/26/decades-later-cold-war-secret-is-revealed/ 〕 A reentry vehicle from the first Hexagon satellite sank to 16,000 feet below the Pacific Ocean after its parachute failed. The retrieved its payload in April 1972 after a lengthy search but the film disintegrated due to the nine months underwater, leaving no usable photographs. Over the duration of the program the lifetime of the individual satellites increased steadily. The final KH-9 operated for up to 275 days. Different versions of the satellite varied in mass; most weighed 11,400 kg or 13,300 kg. 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「KH-9 Hexagon」の詳細全文を読む スポンサード リンク
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