NASA's ICESat mission comes to an end

Red Orbit: NASA’s Orbital Debris Program Office at Johnson Space Center, Houston, has reported that debris from the ICESat spacecraft fell to Earth in the Barents Sea on Monday, Aug. 30, at approximately 5 a.m. EDT.

One of NASA's orbiting sentinels is expected to return to Earth in a few days. The agency's Ice, Cloud, and land Elevation (ICESat) satellite completed a very productive scientific mission earlier this year. NASA lowered the satellite's orbit last month and then decommissioned the spacecraft in preparation for re-entry. It is estimated that the satellite will re-enter the Earth's atmosphere and largely burn up on or about August 29.

ICESat was launched in January 2003, as a three-year mission with a goal of returning science data for five years. It was the first mission of its kind –specifically designed to study Earth's polar regions with a space-based laser altimeter called the Geoscience Laser Altimeter System, or GLAS.

ICESat's lasting legacy will be its impact on the understanding of ice sheet and sea ice dynamics. The mission has led to scientific advances in measuring changes in the mass of the Greenland and Antarctic ice sheets, polar sea ice thickness, vegetation-canopy heights, and the heights of clouds and aerosols. Using ICESat data, scientists identified a network of lakes beneath the Antarctic ice sheet. ICESat introduced new capabilities, technology and methods such as the measurement of sea ice freeboard – or the amount of ice and snow that protrudes above the ocean surface - for estimating sea ice thickness.

"ICESat has been a tremendous scientific success," said Jay Zwally, ICESat's project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "It has provided detailed information on how the Earth's polar ice masses are changing with climate warming, as needed for government policy decisions. In particular, ICESat data showed that the Arctic sea ice has been rapidly thinning, which is critical information for revising predictions of how soon the Arctic Ocean might be mostly ice free in summer. It has also shown how much ice is being lost from Greenland and contributing to sea level rise. Thanks to ICESat we now also know that the Antarctic ice sheet is not losing as much ice as some other studies have shown."…