The Cryosat mission is designed to measure the thickness of the Earth’s polar ice sheets and sea ice, and thus contribute to our understanding of climate change.
The satellite carries an instrument called the SIRAL radar altimeter, which transmits microwave pulses towards the Earth and measures the time taken for them to bounce back. By measuring the travel time and knowing the speed of light, it is possible to calculate the distance between the satellite and the surface below. The height of sea ice can then be inferred from this distance measurement.
Cryosat was launched on 8 April 2010 and has been operational since then. It flies over both poles every 36 hours, providing us with a near-global coverage of Arctic and Antarctic sea ice conditions.
The data from Cryosat are essential for understanding how fast the ice sheets are shrinking in response to global warming. They are also important for improving our predictions of future sea level rise.