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The Extended Duration Orbiter (EDO) program was a project by NASA to prepare for long-term (months) microgravity research aboard Space Station Freedom, which later evolved into the International Space Station. Scientists and NASA needed practical experience in managing progressively longer times for their experiments. The original space shuttle configuration usually provided a week to ten days of spaceflight. Several research projects and hardware components were part of the project, of which the EDO-pallet was one of the most visible, contracted by Rockwell International. The first orbiter outfitted with the EDO hardware configuration was ''Endeavour'', during its construction, and its last EDO flight was STS-67, in 1995.〔〔 〕 ''Endeavour's'' EDO modifications were removed in 1996 as part of routine maintenance, to reduce the orbiter's weight prior to STS-89.〔 ''Columbia'' was outfitted for EDO flight during its maintenance period from August 10, 1991, through February 9, 1992, prior to STS-50, which was the first EDO flight.〔 From 1992, through 1994, ''Atlantis'' went through a maintenance period, during which ''Atlantis'' was modified to have the provisions needed for EDO capability, but NASA chose not to proceed with the final modifications, and ''Atlantis'' does not have EDO capability.〔 The EDO-pallet used in these orbiter configurations was destroyed in the ''Columbia'' accident. ==EDO pallet== The Extended Duration Orbiter Cryogenic kit (EDO-pallet or CRYO) is a assembly of equipment which attached vertically to the payload bay rear bulkhead of an orbiter, and allowed the orbiter to support a flight of up to 16 days duration.〔 The equipment includes cryogenic tanks, associated control panels, and avionics equipment. Although ''Atlantis'' was partially upgraded to accommodate the EDO, only ''Columbia'' and ''Endeavour'' actually flew with the pallet. The pallet made its debut on STS-50, and was lost on mission STS-107, the Space Shuttle Columbia disaster. Initially, NASA considered adding a second EDO pallet to ''Endeavour'', placed in front of the first, for a total of thirteen tank sets, that would have allowed an orbiter to remain in space for 28 days, but managers decided against it when the International Space Station assembly began, and instead removed the EDO capability from the orbiter, to reduce its weight and allow it to carry more cargo to the ISS.〔 No replacement for the pallet was planned, since the Station-to-Shuttle Power Transfer System provided much of the same abilities, and the 2011 retirement of the shuttle fleet made it redundant. 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「Extended Duration Orbiter」の詳細全文を読む スポンサード リンク
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