CRISTAL (Sentinel 9)

CRISTAL [Thales Alenia Space]

CRISTAL (Copernicus Polar Ice and Snow Topography Altimeter) or Sentinel 9 is an earth observation mission in the framework of ESA's Copernicus program.

CRISTAL will carry a multi-frequency radar altimeter and microwave radiometer to measure and monitor sea-ice thickness and overlying snow depth. It would also measure and monitor changes in the height of ice sheets and glaciers around the world. Measurements of sea-ice thickness would support maritime operations in polar oceans and, in the longer term would help in the planning of activities in the polar regions. Since inter-annual sea-ice variability is sensitive to climate change, the mission would contribute to a better understand of climate processes.

The IRIS dual-frequency Ku/Ka bands radar altimeter to measure and monitor sea-ice thickness and overlying snow depth. Measurements of sea-ice thickness will support maritime operations and they will help in the planning of activities in the polar regions. IRIS will also measure and monitor changes in the height of ice sheets and glaciers around the world, thanks to its interferometric radar mode. IRIS will significantly improve the measurement accuracy of its predecessor SIRAL-2 (a Ku band only altimeter on board ESA’s CryoSat-2 Earth Explorer mission) thanks to the dual frequency operation and by adding the measurement of sea surface height as part of the mission objectives.

In July 2020, ESA signed a contract with Airbus Defence and Space as a prime contractor to build the satellite. Thales Alenia Space will build the altimeter.