Mar 17 2002
From The Space Library
Two spacecraft comprising the Gravity Recovery and Climate Experiment (GRACE) launched on a single rocket vehicle from Russia’s Plesetsk Cosmodrome. The five-year mission’s main purpose was to map variations in Earth’s gravity field, using the GPS and a microwave ranging system to measure the distance between the mission’s two identical satellites~nicknamed Tom and Jerry. The two craft were to monitor each other while flying in a polar orbit 500 kilometers (311 miles) above Earth. This mission, to study measurements of gravity variations, could help scientists understand better the changes in the transport of mass around the planet. Changes in mass, such as ocean currents, ground-water storage, and mass within Earth, can affect climate and other aspects of the planet’s environment. The GRACE mission was a partnership between NASA and the Deutsche Zentrum für Luft- und Raumfahrt (the German Aerospace Center). (University of Texas Center for Space Research, “GRACE: Mission Overview,” http://www.csr.utexas.edu/grace/overview.html (accessed 11 August 2002); Warren E. Leary, “New Satellites To Map Gravity More Precisely,” New York Times, 19 March 2002.
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