Successful launch for ESA's CryoSat-2 ice mission
8 April 2010, by Tamera Jones
At 14:57 GMT on Thursday 8 April, the European Space Agency successfully launched its ice mission CryoSat-2 from the Baikonur cosmodrome in Kazakhstan.
Cryosat in the clean room.
The long-awaited satellite will measure both the shape and thickness of ice in the Arctic and Antarctica with unprecedented accuracy.
The poles are warming up faster than any other region on Earth. Arctic sea ice is both thinning and receding, Antarctic ice sheets are either disintegrating or at risk of collapse and glaciers are retreating. But scientists don't yet know how melting polar ice affects ocean circulation patterns, sea level and the global climate.
CryoSat-2 is set to provide scientists with answers to these hotly debated questions by telling them precisely how ice cover at the poles is changing – the mission has been designed to measure changes in ice thickness to the nearest centimetre.
It'll do this using an instrument called an altimeter which fires pulses of microwave energy down at the ice and then records how long it takes for the pulses of energy to return.
Scientists will be able to use the difference between how long it takes for the echoes to return from the top of ice floes and from the water in cracks in the ice to calculate how thick the ice is. Essentially the aim is to measure the freeboard – the part of the ice that sits above the waterline.
How CryoSat-2's radar will measure ice thickness from space.
Receding summer sea ice in the Arctic means that the Arctic Ocean is more vulnerable to strong polar winds. These winds effectively 'spin up' the Arctic Ocean, which could affect ocean circulation patterns not just in the Arctic, but as far away as the North Atlantic, which could ultimately affect Britain's weather.
CryoSat-2 will tell scientists how winds affect the Arctic Ocean by measuring differences in the height of the sea surface exposed between ice floes.
'There's really no other way to do this other by using satellites, because satellites give so much coverage,' says CryoSat-2's chief scientist Professor Duncan Wingham from the Centre for Polar Observation and Modelling at University College London.
A second antenna on the tent-shaped satellite will measure the ice's shape and so tell researchers about changes in the slopes and ridges at the edges of the great Antarctic and Greenland ice sheets. This is crucial because the edges of ice sheets are where melting is happening the fastest.
Launch day was tense for many scientists, not least Wingham. He first proposed the satellite in 1999. Six years later, CryoSat-1 was launched. But after launch, mission control lost contact with the satellite.
CryoSat-1 crashed into the northern Arctic Ocean shortly after lift-off from the Plesetsk cosmodrome in northern Russia on 8 October 2005. The loss was blamed on a fault in the rocket's onboard flight control system, which has since been rectified in other launchers.
'I was stunned initially. You know there's a risk of losing a satellite after launch, however you don't think it's going to happen to you,' says Wingham.
Once he'd got over the shock of the loss, Wingham set to work persuading ESA that the mission was worthwhile enough to try again. Indeed ESA considered the mission important enough that within four months plans were in place for CryoSat-2. 'We're exceptionally proud of this achievement,' says Wingham.
CryoSat-2 was launched using a Dnepr rocket – a converted intercontinental ballistic missile. It's a slightly different launcher from the one used to launch CryoSat-1.
'But that's got nothing to do with failure with the first rocket. There's a shortfall of launchers on the worldwide market, but the Dnepr rocket has shown a reliable track record since it was used in 1999,' adds Wingham.
CryoSat-2's ability to monitor changes at the poles will surpass the abilities of earlier ESA satellites – its radar has been specifically designed for the task and its orbit will cover much more of the Arctic and Antarctica than has previously been possible.
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