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The Gravity Recovery And Climate Experiment (GRACE), a joint mission of NASA and the German Aerospace Center, has been making detailed measurements of Earth's gravity field anomalies since its launch in March 2002. Gravity is determined by mass. By measuring gravity anomalies, GRACE shows how mass is distributed around the planet and how it varies over time. Data from the GRACE satellites is an important tool for studying Earth's ocean, geology, and climate. GRACE is a collaborative endeavor involving the Center for Space Research at the University of Texas, Austin; NASA's Jet Propulsion Laboratory, Pasadena, Calif.; the German Space Agency and Germany's National Research Center for Geosciences, Potsdam.〔(【引用サイトリンク】 title =Grace Space Twins Set to Team Up to Track Earth's Water and Gravity )〕 The Jet Propulsion Laboratory is responsible for the overall mission management under the NASA ESSP program. The principal investigator is Dr. Byron Tapley of the University of Texas Center for Space Research, and the co-principal investigator is Dr. Christoph Reigber of the GeoForschungsZentrum (GFZ) Potsdam. The GRACE satellites were launched from Plesetsk Cosmodrome, Russia on a Rockot (SS-19 + Breeze upper stage) launch vehicle, on March 17, 2002. The spacecraft were launched to an initial altitude of approximately 500 km at a near-polar inclination of 89°. The satellites are separated by approximately 200 km along their orbit track. GRACE has far exceeded its designed five-year lifespan. the GRACE spacecraft are expected to remain in a slowly decaying orbit until 2015 or 2016. Its successor, GRACE Follow-On, is expected to launch in 2017.〔(【引用サイトリンク】url=https://www.ae.utexas.edu/news/features/grace-follow-on )〕 == Discoveries and applications == The monthly gravity anomalies maps generated by GRACE are up to 1,000 times more accurate than previous maps, substantially improving the accuracy of many techniques used by oceanographers, hydrologists, glaciologists, geologists and other scientists to study phenomena that influence climate.〔(【引用サイトリンク】 title =New Gravity Mission on Track to Map Earth's Shifty Mass )〕 From the thinning of ice sheets to the flow of water through aquifers and the slow currents of magma inside Earth, measurements of the amount of mass involved provided by GRACE help scientists better understand these important natural processes. 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「Gravity Recovery and Climate Experiment」の詳細全文を読む スポンサード リンク
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