The first aim of the CryoSat-2 satellite is to monitor very precisely the changes in the thickness of the polar ice sheets and floating sea ice. This ESA mission will allow us to answer how global climate change is causing the polar ice caps to shrink. The main payload of the CryoSat-2 satellite is an radar altimeter named SIRAL (Synthetic aperture radar Interferometric Radar Altimeter).
isardSAT is involved in the CryoSat-2 mission with the absolute calibration of SIRAL using transponders.
The purpose of any absolute calibration is to get an independent value of the same target from the instrument to be calibrated. In other words, to make the instrument measure a well known target. This value has to be obtained as accurately as possible and in turn it also has to be calibrated. A transponder (TRP), that can be seen by a radar as a point target, has been identified to be the best method in order to obtain the independent measurement. isardSAT will be using an ESA transponder located in the Svalbard station to absolute calibrate SIRAL.
isardSAT will also retrieve the range and sigma-0 bias using cross-calibration methods (with EnviSat and Jason-1 altimeters).