CryoSat carried a radar altimeter to acquire accurate measurements of the thickness of floating sea ice so that annual variations could be detected. It would also permit survey the surface of ice sheets accurately enough to detect small changes. After a seven-year development program, the spacecraft was lost due to a software error in the guidance of the Rokot launch vehicle that was to have placed it in orbit.

CryoSat carried a radar altimeter to acquire accurate measurements of the thickness of floating sea ice so that annual variations could be detected. It would also permit survey the surface of ice sheets accurately enough to detect small changes. After a seven-year development program, the spacecraft was lost due to a software error in the guidance of the Rokot launch vehicle that was to have placed it in orbit. Since it operated in SAR and Interferometric modes, the altimeter was called SIRAL (SAR Interferometric Radar Altimeter). CryoSat would have orbited at an unusually high inclination, reaching latitudes of 88° North and South. CryoSat would have achieved improved spatial resolution of 250 m in the along-track direction using the Synthetic Aperture technique.

CryoSat's orbit was not sun-synchronous and would have gone through frequent eclipse phases. This presented thermal challenges in the satellite design. CryoSat also did not have any deployable solar panels - - in fact the satellite had no moving parts at all, except for some valves in the propulsion system. The solar panels were fixed to the satellite body, forming a 'roof' at an optimized angle, which provided adequate power under all orbital conditions and still fitted within the launch vehicle.

Cryosat had an intended mission duration of 3.5 years in its non Sun-synchronous, circular 717 km orbit inclined at 92 degrees. The payload consisted of the SIRAL; the DORIS receiver (which received signals from a global network of radio beacons for orbit determination); a laser retroreflector; an X-band antenna (to transmit the huge volume of SIRAL measurement data to the ground when the satellite was above the horizon at Kiruna, Sweden); an S-band helix antenna (to receive telecommands from the ground and transmit status and monitoring information); and three star trackers. The loss of the spacecraft on launch brought to a sorry end a seven-year development program. Milestones included:

• 8 October 2005 - CryoSat mission lost due to an anomaly in the launch sequence
• 26 September 2005 - CryoSat sealed into payload fairing
• September 2005 - CryoSat arrives at launch site in Plesetsk, Russia
• July 2005 - Environmental testing successfully completed at IABG
• June-July 2005 - Start of Flight Acceptance Review
• March 2005 - Sea-ice validation campaign carried out in Baltic Sea.
• October 2004 - Start of integrations of the SIRAL instrument into the spacecraft at IABG (Ottobrunn, Germany).
• September 2004 - Pre-launch series of validation campaigns completed in Arctic.
• September 2004 - Mass properties, separation and vibration tests completed at IABG (Ottobrunn, Germany).
• August 2004 - Spacecraft integration completed at Astrium GmbH - shipped to IABG for environmental testing.
• June 2004 - First of the six Arctic validation campaigns successfully completed.
• June 2004 - Integration of the spacecraft at the Prime Contractor Astrium GmbH's facility in Friedrichshafen, Germany.
• April 2004 - Critical Design Review
• March 2004 - In preparation for a series of validation campaigns in the Arctic, the ASIRAS (Airborne Synthetic Aperture and Interferometric Radar Altimeter System) instrument, which simulates CryoSat measurements from an aircraft, was successfully tested over Svalbard, Norway.
• October 2003 - Installation and testing of payload data processing facility began at the ground station in Kiruna, Sweden.
• September 2003 - Draft CryoSat Validation Implementation Plan released.
• July 2003 - Ground Segment Design Review successfully completed. Industrial integration of scientific data processing algorithms begins.
• June 2003 - First part of Space Segment Critical Design Review successfully completed. EADS Astrium GmbH began integration of the spacecraft in Friedrichshaven, Germany.
• July 2002 - Rokot selected as launcher for CryoSat
• February 2002 - Signature with Astrium as prime contractor for the satellite development
• July 2001 - Start of construction phases C/D
• March 2001 - Phase B completed
• August 2000 - Selection of industrial consortia finalized. Start of phase B
• February 2000 - Kick-off for feasibility study
• April 1999 - CryoSat selected
• January/February 1999 - Evaluation of proposals
• July 1998 - Call for proposals

Design Life: 3.5 years. Length: 4.60 m (15.00 ft). Basic Diameter: 2.20 m (7.20 ft). Maximum Diameter: 2.34 m (7.67 ft). Mass: 669 kg (1,474 lb). Main Engine Propellants: 36 kg (79 lb).

• 2005 October 8 - CryoSat - Launch Site: Plesetsk. Launch Vehicle: UR-100N. FAILURE: The first stage burned to depletion due to a missing command in the software sequence. This resulted in the second stage failing to separate. Mass: 717 kg (1,580 lb).

  ESA Earth Explorer 1 mission failed to orbit. The satellite was to have used radar altimetry for environmental survey of polar ice with great accuracy. Delayed from November 2004, March 25, June 24, July 11, September 15 and 27, 2005.