19 March 2007: The CryoSat-2 satellite replaces CryoSat, which was lost as a result of launch failure in October 2005. With climate change bringing about the threat of receding ice cover, the need to understand the extent to which this may be happening is even more relevant today than it was when the first CryoSat was selected for development in 1999. The International Polar Year 2007-2008 (IPY) will focus resources on making measurements of our polar environments. The loss of the original CryoSat prevented it contributing to this effort but the exploitation of CryoSat-2 will benefit from the IPY.
Although the impact of climate change is expected to be amplified at the poles, it is extremely difficult to determine what effect this is having on the polar ice cover. Recent reports of receding sea ice in the Arctic and the break-up of the edges of the massive Antarctic ice sheet are much in the public eye. On the other hand, there have also been reports of the ice at the North Pole being thicker than usual.
Scheduled for launch in 2009, CryoSat-2 will measure fluctuations in the thickness of ice on both land and sea to provide conclusive evidence as to whether there is indeed a trend towards diminishing ice cover. Moreover, since ice plays such an important role in the Earth system, predicting future climate and sea level depends on the data that CryoSat-2 will realise.
In the year since the go-ahead to build CryoSat-2, much has been achieved and the project has just passed an important milestone, that being the Critical Design Review during which all the changes to the design were scrutinised. Notable among the changes, is the decision to have the satellite carry a back-up for the main payload, the SAR/Interferometric Radar Altimeter (SIRAL). This means fitting in a complete second set of electronics.
Radar altimeters have been flown in space before, but the SIRAL is a radar with a difference. Its sophisticated design encompasses enhanced resolution and observing capabilities to meet the challenges of acquiring accurate measurements of the thickness of floating sea ice, whilst also being able to survey the surface of vast ice sheets accurately enough to detect small changes.