ICESat (Ice, Cloud, and land Elevation Satellite), part of NASA's Earth Observing System, was a satellite mission for measuring ice sheet mass balance, cloud and aerosol heights, as well as land topography and vegetation characteristics. ICESat was launched 13 January 2003 on a Delta II rocket from Vandenberg Air Force Base in California into a near-circular, near-polar orbit with an altitude of approximately 600 km. It operated for seven years before being retired in February 2010, after its scientific payload shut down and scientists were unable to restart it.