CryoSat-2, Europe's first ice mission, is an advanced radar altimeter specifically designed to monitor the most dynamic sections of Earth's cryosphere. It borrows synthetic aperture radar and interferometry techniques from standard imaging radar missions to sharpen its accuracy over rugged ice sheet margins and sea ice in polar waters. CryoSat-2 measures 'freeboard', the difference in height between sea ice and adjacent water, as well as ice sheet altitude and tracking changes in ice thickness.

CryoSat-2's primary payload is the SAR/Interferometric Radar Altimeter (SIRAL) which has extended capabilities to meet the measurement requirements for ice-sheet elevation and sea-ice freeboard.

CryoSat-2 carries also three star trackers for measuring the orientation of the baseline. In addition, a radio receiver called Doppler Orbit and Radio Positioning Integration by Satellite (DORIS) and a small laser retroreflector ensures that CryoSat-2's position will be accurately tracked.

More detailed information on CryoSat instruments is available here.
 

The ESA's Cryosat-2 will use radar to measure the thickness of ice on the Earth. Image credit: ESA - AOS Medialabs