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CryoSat is an ESA programme to monitor variations in the extent and thickness of polar ice through use of a satellite in low Earth orbit. The information provided about the behaviour of coastal glaciers that drain thinning ice sheets will be key to better predictions of future sea level rise. The CryoSat-1 spacecraft was lost in a launch failure in 2005, however the programme was resumed with the successful launch of a replacement, CryoSat-2, launched on 8 April 2010.〔(Nature ) news brief ''The week in science'' dated April 15, 2010〕〔(European Space Agency ) article ''ESA confirms CryoSat recovery mission'' dated February 24, 2006〕 CryoSat is operated from the European Space Operations Centre (ESOC) in Darmstadt, Germany. ==Description== CryoSat's primary instrument is SIRAL (SAR / Interferometric Radar Altimeter). SIRAL operates in one of three modes, depending on where (above the Earth's surface) CryoSat was flying. Over the oceans and ice sheet interiors, CryoSat operates like a traditional radar altimeter. Over sea ice, coherently transmitted echoes are combined (synthetic aperture processing) to reduce the surface footprint so that CryoSat could map smaller ice floes. CryoSat's most advanced mode is used around the ice sheet margins and over mountain glaciers. Here, the altimeter performs synthetic aperture processing and uses a second antenna as an interferometer to determine the across-track angle to the earliest radar return. This provides the exact surface location being measured when the surface is sloping. The original CryoSat was proposed in 1998 by Duncan Wingham of University College London. The satellite's planned three-year mission was to survey natural and human driven changes in the cryosphere on Earth. It was designed to provide much more accurate data on the rate of change of the surface elevation of the polar ice sheets and sea ice thickness. It was the first ESA Earth Sciences satellite selected through open, scientific competition.〔(CPOM Website )〕 It was destroyed on launch October 8, 2005. The existing satellite is therefore CryoSat-2, but the mission is still known as simply CryoSat.〔http://www.esa.int/esaLP/ESAOMH1VMOC_LPcryosat_0.html〕 Although largely the same as the original satellite a number of key improvements were included in CryoSat-2. The most significant was the decision to provide a fully duplicated payload to enable the mission to continue if a fault caused the loss of the SIRAL radar, but there were many other changes "under the hood". Some of these were caused by obsolescence in the original design, some improved reliability and others made the satellite easier to operate. Despite all the changes the mission remains the same and the performance, in terms of measurement capability and accuracy, remains the same. , the launch was scheduled for February 25, 2010 with a Dnepr rocket from the Baikonur Cosmodrome,〔http://www.esa.int/esaCP/SEM1UZLJ74G_index_0.html〕 but this was delayed. The CryoSat 2 launched on April 8, 2010 at 13:57 UTC.〔http://www.ukspaceagency.bis.gov.uk/〕〔http://www.nature.com/news/2010/100330/full/464658a.html〕 For positioning purposes, CryoSat included a DORIS receiver, a laser retroreflector and three star trackers. The ERS-1 and ERS-2 satellites were precursors that tested the techniques used by CryoSat. 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「CryoSat」の詳細全文を読む スポンサード リンク
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