Cryosat

Cryosat-2 is an altimetry satellite built by the European Space Agency dedicated to polar observation. It will embark on a three-and-a half-year mission to determine variations in the thickness of the Earth's continental ice sheets and marine ice cover, and to test the prediction of thinning arctic ice due to global warming.

The Cryosat-2 satellite will study continental and sea ice. Its orbit -at an inclination of about 92 degrees and an altitude of 717 kilometers- will cover almost all polar regions. Cryosat-2 will carry an altimeter/interferometer called Siral and a Doris instrument, but no radiometer. Siral is a Ku-band instrument (13.575 GHz) operating in three modes :

• Low-resolution, nadir-looking altimeter mode, provides conventional pulse-width limited altimetry over central ice caps, oceans and land,
• SAR mode improves along-trackresolution (~250 m) over sea ice by significantly increased pulse repetition frequency and complex ground processing,
• SAR interferometric mode adds a second receive chain to measure the cross track-angle of arrival of the echo over topographic surfaces at the margins of ice caps.

Current plans are for Cryosat to operate over the oceans for validation purposes, in low-resolution mode. That means that the ground segments will be able to process oceanic altimetry measurements acquired by Siral. Direct radiometric corrections, however, will not be possible.

Dynamic topography data of medium quality, but from a new orbit, might therefore be available. These data could be combined with measurements from other dedicated altimetry missions.

One first satellite Cryosat was lost on launch, on October 8, 2005, due to an anomaly in the launch sequence. A replacement will be launched inSpring 2010.

More information on the mission (Esa website)