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The Advanced Cryogenic Evolved Stage (ACES)—formerly the ''Advanced Common Evolved Stage''—is a proposed liquid oxygen/liquid hydrogen upper stage rocket for use on the Vulcan space launch vehicle. The design concept is from the U.S. company United Launch Alliance (ULA).〔 ACES is intended to boost satellite payloads to geosynchronous orbit or, in the case of an interplanetary space probe, to or near to escape velocity. Other alternative uses include a proposal to provide in-space propellant depots in LEO or at that could be used as way-stations for other rockets to stop and refuel on the way to beyond-LEO or interplanetary missions, and to provide the high-energy technical capacity for the cleanup of space debris.〔 , ULA announced conceptual plans to transition the Vulcan rocket to the ACES second stage after approximately 2023. Vulcan will initially launch with the Centaur upper stage, beginning with its first flight no earlier than 2019. == History == Originally proposed as the ''Advanced Common Evolved Stage'' by ULA in the late 2000s, ACES was intended to boost satellite payloads to geosynchronous orbit or, in the case of an interplanetary space probe, to or near to escape velocity. Other alternative uses included a proposal to provide in-space propellant depots in LEO or at that could be used as way-stations for other rockets to stop and refuel on the way to beyond-LEO or interplanetary missions, and to provide the high-energy technical capacity for the cleanup of space debris.〔 The late-2000s ACES proposal by ULA had a predecessor at Lockheed Martin, prior to the merger of Boeing and Lockheed Martin launch vehicle manufacturing and operations to form ULA in 2006. Known then as the ''Lockheed Martin common-stage concept'', the upper stage was intended to "provide efficient, robust in-space transportation, and take advantage of the high-mass fraction that is enabled by Centaur’s moncoque () design and its common bulkhead to minimize combined LO2/LH2 boil off. ... application of long-duration LO2/LH2 in-space propulsion technology (be expected to ) result in significant launch cost savings for space exploration. ... passive long duration capability (be achieved ) by implementing cross cutting Cryogenic Operation for Long Duration (COLD) technologies, and improve cryogenic storage capability by more than two orders of magnitude compared to existing large-scale flight-proven systems."〔(2005: Atlas Centaur Extensibility to Long-Duration In-Space Applications ), Bernard F. Kutter, Frank Zegler, et al, Lockheed Martin Space Systems Company, (AIAA 2005-6738), accessed 20 October 2015.〕 A study funded by NASA led to the development of the Lockheed Martin concept known as ACES, under the original name of Advanced ''Cryogenic'' Evolved Stage as of 2006.〔(2006: Centaur Extensibility For Long Duration ), Gerard Szatkoski, et al, NASA/KSC and Lockheed Martin Space Systems Company, (AIAA Space 2006 Conference Paper no. 60196), accessed 20 October 2015.〕 In April 2015, after ULA had announced the end of production of the Delta IV Medium in 2019 and the Delta IV Heavy in the mid-2020s, ULA renamed the stage the ''Advanced Cryogenic Evolved Stage'', as ACES would in this case serve as the second stage on only a single launch vehicle, the Vulcan, beginning no earlier than 2023.〔 〕 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「Advanced Cryogenic Evolved Stage」の詳細全文を読む スポンサード リンク
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