First European Ice Monitoring Satellite Flies Saturday

LONDON, UK, October 6, 2005 (ENS) - A satellite will be launched from a Russian space center near the Arctic Circle on Saturday that carries instuments designed to measure the thickness of the polar ice caps. During its 1,000 day mission CryoSat, the new European Space Agency ice-monitoring satellite, will attempt to determine how quickly the ice caps are thinning.

Scheduled for launch on October 8, CryoSat is the first in a new class of European Space Agency (ESA) Earth Observation spacecraft known as Earth Explorers, which are small research missions designed to address critical issues of Earth science. This ice-dedicated satellite is a first for Europe, but follows in a long tradition of European polar exploration.

Today Arctic and Antarctic sea ice is routinely monitored by satellite – although CryoSat will be the first radar altimeter optimized for sea ice. Climate modelling suggests the frozen ends of the Earth will exhibit the greatest sensitivity to climate change, and represent the best means to estimate its future extent. Reports of record lows for the extent of Arctic summer sea ice precede the launch of CryoSat.


Artist's impression of CryoSat in orbit. (Image courtesy ESA)
The concept behind the CryoSat mission, approved in 1999, is to respond to the current debate on global warming and the effect this may be having on Earth's polar masses.

The satellite's main payload is an instrument called Synthetic Aperture Interferometric Radar Altimeter (SIRAL). Previous radar altimeters were optimized for operations over the ocean and land. SIRAL is the first sensor of its kind designed for ice.

CryoSat is about to start delivering a dynamic picture of shifts across both polar regions, its radar altimeter returning a detailed record of changes in the thickness of marine ice cover and changes in the elevation of ice sheets on land over a continuous three year period, with an accuracy of one centimeter.

CryoSat will better ESA’s previous missions by flying within two degrees of the South Pole, providing the most comprehensive dataset on polar ice mass variations to-date.

British Science Minister Lord Sainsbury said, "CryoSat will be crucial to our understanding of one of our planet's most fragile areas. The UK's world-class science and innovative engineering has put us right at the heart of this cutting edge mission."

The mission is scheduled to blast off from the Khrunichev Space Centre, Plesetsk, Russia, just a few degrees south of the Arctic Circle in the Archangel region of Russia.

Plesetsk is Russia's most northerly rocket base, used to place mainly military satellites into polar orbit. Until recently Plesetsk was the busiest launch site in the world. It is the only orbital launch site located within European territory.

For 25 years, until 1983, the existence of Plesetsk was a Russian state secret, but after the end of the Cold War the Cosmodrome was opened up for commercial launch services. Today Soyuz, Cosmos 3-M, Rockot and Tsyklon launch vehicles are flown from Plesetsk.


An artist's drawing of the CryoSat spacecraft in flight. (Image courtesy ESA)
CryoSat will be the ESA's first mission launched from Plesetsk, although not the last - follow-up Earth Explorers will be flown from the same site.

In a first for the European Space Agency, CryoSat will be launched from a Russian Rockot vehicle - a converted SS-19 ballistic missile with an additional Breeze-KM upper stage - optimized for delivering up to 1950 kilograms into low-Earth orbit.

The SS-19 was designed as a weapon of war during the early 1970s - a rapid-launching liquid-propellant missile for nuclear warheads, based in silos across the old Soviet Union. Some 150 of these missiles were declared excess in military terms by the Strategic Talks on Arms Reduction Treaty (START) agreements signed by the United States and the Soviet Union in 1990 and 1991, but were permitted for re-use as civilian launchers.

Once launched into orbit 717 kilometers (445 miles) above the surface of the Earth, CryoSat will maintain communication with the ESA team with electronic radio signals, relayed through a single ESA ground station at Kiruna, in northern Sweden.

From this site, contact can be established for about 10 minutes 11 times a day, during which commands can be sent to the satellite and its data downloaded. Kiruna is linked to the CryoSat Mission Control Centre, at ESA's European Space Operations Centre in Darmstadt, Germany.

The Cryosat mission was proposed by UK scientist Professor Duncan Wingham from the Natural Environment Research Council's Centre for Polar Observation and Modelling.


Duncan Wingham is professor of climate physics at University College London, and director of the NERC Centre for Polar Observation & Modelling. He is also principal scientist of the European Space Agency CryoSat Satellite Mission, the first ESA Earth Sciences satellite selected through open, scientific competition. (Photo courtesy CPOM)
Professor Wingham said, "The great difficulty at present is to figure out whether changes in ice cover are due to melting or to changes in the winds that shift the ice around. The only way to do this is to examine the entire Arctic at the same time. CryoSat is the first satellite designed to do this job, and after six years in the making, we are really looking forward to getting our hands on the data."

The Natural Environment Research Council's Chief Executive Professor Alan Thorpe said, "We know the Arctic is one of the fastest warming regions on the planet and that it is particularly sensitive to climate change. The reports of a major loss of Arctic sea ice cover in August and September only serve to highlight the importance of the three-year mission."

The satellite will do more than measure Arctic sea ice. Its orbit takes it over the major ice sheets of Antarctica in the south and Greenland in the north. Scientists will be able to use CryoSat data to accurately predict sea level rise caused by melting ice sheets.

CryoSat's altimeter has the ability to measure ice sheets and sea ice with unprecedented accuracy. Until now satellites have been unable to monitor melting ice at the point where it is most significant - at the ice edge.

The altimeter's ability to pick out sea ice of around one kilometer in diameter is expected to improve annual melt estimations.

CryoSat's data will be validated by comparison with direct measurements taken on Earth in the polar regions. These include a mix of surface measurements by field parties, systems mounted on helicopters and aircraft, and measurements from polar research ships.

The Cryosat mission will contribute data to the International Global Earth Observing Strategy, a process to harmonize space and Earth based observation systems, which includes a dedicated Cryosphere theme.

British industry has played a key role in the mission technology. UK space software experts at SciSys developed the onboard application software that will be responsible for controlling the precise orbit and attitude of the spacecraft. It will also handle all communications with ground control.