August 31, 2016

Mission

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ESA's Earth Explorer CryoSat mission, launched on 8 April 2010, is dedicated to precise monitoring of the changes in the thickness of marine ice floating in the polar oceans and variations in the thickness of the vast ice sheets that overlie Greenland and Antarctica.

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CryoSat-2 Satellite - Credits ESA - P. Carril

The CryoSat-2 satellite replaces the original CryoSat, which was lost owing to a launch failure in October 2005. Following the loss, the mission was judged to be even more important than when it was first selected for development, and the decision to rebuild was taken. Almost exactly four years to the day after that decision, the new CryoSat-2, with a number of improvements, was ready for launch.

The aim of the CryoSat mission is to determine variations in the thickness of the Earth's marine ice cover and understand the extent to which the Antarctic and Greenland ice sheets are contributing to global sea level rise.

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Greenland ice-sheet height - © Helm et al., The Cryosphere, 2014

To reach the scientific objective, the payload is constituted of the following instruments:

  • the primary payload: SAR/Interferometric Radar Altimeter (SIRAL), which has extended capabilities to meet the measurement requirements for ice-sheet elevation and sea-ice freeboard;
  • a radio receiver called Doppler Orbit and Radio Positioning Integration by Satellite (DORIS, supplied by CNES) for the precise orbit determination and the real time positioning;
  • a laser retro-reflector for the accurate orbit computation;
  • three star trackers for measuring the orientation of the baseline.

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Antarctic ice-sheet height - © Helm et al., The Cryosphere, 2014

Even if the mission is mainly dedicated to the ice, the first results shown a real interest of Cryosat-2 measurements to study the oceans. In the face of the scientific community's insistence, ESA developed and set up a dedicated processing chain in 2014.

CryoSat was launched from the Baikonur Cosmodrome, Kazakhstan by a Russian/Ukrainian Dnepr based on an SS-18 intercontinental ballistic missile. The launcher was provided by the International Space Company Kosmotras.

The mission duration has been extended by ESA until February 2017.

The mission control is at ESA's European Satellite Operations Centre (ESOC) in Darmstadt, Germany.
The ground station receiving the science data are ESA's ground stations in Kiruna and Esrange, Sweden.
The data are distributed directly to users from the ground station in Kiruna.
The distribution and mission planning are managed via ESA's Centre for Earth Observation (ESRIN) in Frascati, Italy.
The long-term archive is in a dedicated facility at the French space agency CNES in Toulouse, France.

CNES is involved in the Cryosat-2 mission in different ways. It ensures:

  • the DORIS instrument MCO and the processing of the anomalies in orbit,
  • the availability of the DORIS ground facilities (beacon ground network),
  • the production of orbit in real time and delayed time thanks to on-board DORIS and the processing on ground ensured by the SSALTO multi-mission centre,
  • the long-term archive, through a service contract, using a generic service of CNES computing facility, the STAF,
  • the use of Cryosat-2 data in the SSALTO DUACS system.

Even if it lacks an on-board radiometer to make it a real altimetry mission over ocean, it enables to have a reinforced altimetry constellation thanks to the contribution of this complementary mission.

All Cryosat news on ESA's website.

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