Launch of ICESat
January 16, 2003
NASA’s Ice, Cloud and Land Elevation satellite (ICESat) lifted off on January 11 from Vandenberg Air Force Base, Calif., at 4:45 a.m. PST aboard Boeing’s Delta II rocket. Once in its final orbital position, in approximately two weeks, ICESat will be approximately 373 miles (600 kilometers) above the Earth.
ICESat is the latest in a series of Earth Observing System spacecraft. The main goal of ICESat is to quantify ice sheet growth or retreat and to thereby answer questions concerning many related aspects of the Earth’s climate system, including global climate change and changes in sea level. ICESat's primary sensor is the Geoscience Laser Altimetry System (GLAS). GLAS will continuously emit laser pulses at a rate of 40 per second and will measure precisely how long it takes photons in a laser pulse to pass through the atmosphere to the Earth's surface, and then upon reflection from the surface, travel back to the satellite. The "exact" distance from ICESat to a particular point on the Earth's surface can then be calculated and changes in this distance as a result of differences in ice sheet thickness, for example, can be determined.