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Airborne Launch Assist Space Access
Airborne Launch Assist Space Access, or DARPA ALASA is a canceled program of the US defense technology agency DARPA "designed to produce a rocket capable of launching a 100-pound satellite into low Earth orbit for less than $1 million."〔 The program was conceived, then announced in 2011, and funded development work began in 2012. The project was terminated in late 2015.
==Background==
Traditional launch methods of satellites are too costly to put small payloads into orbit without a larger payload accompanying it to make the launch worth the expense. Current launches of sub-100-pound satellites are performed as "piggyback payloads" on launches of much larger spacecraft, usually headed for geostationary orbit, and are released at the altitude of the primary payload. In addition, range costs of operating from ground-based infrastructure have escalated as they have aged, accounting for up to 35 percent of the launch cost. This restricts the number of light satellite launches to 10-12 per year, which could be increased if small payloads could be launched into space affordably and without ground range constraints. Air-launching satellites was first seriously considered during the 1950s and 1960s, but small payloads in the 100-pound class at the time did not have effective capabilities, so the method was overlooked. The first air-launched rocket to put a satellite into orbit was the Orbital Sciences Corporation Pegasus, which did it on 13 June 1990; however, it is currently deployed from a heavily modified and expensive Lockheed L-1011 airliner. The ALASA program's objective is to use an unmodified aircraft platform (except for software) that does not have to be dedicated to the mission to place a 100 lb satellite into orbit that requires only 24 hours notice to integrate and launch the payload, with the ability to re-plan the launch in flight and relocate the aircraft to any civilian airport or military airfield in a crisis situation, while using onboard GPS/inertial position reporting rather than ground-based radar tracking.〔(Darpa Revisits Air Launch With Focus On Cost ) - Aviationweek.com, 25 July 2012〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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