Samstag, 28. November 2009

Mission CryoSat-2

The ice in the polar regions play a crucial role in earths climate, but the quantification of the ice and measuring it's change trough time is difficult.
Satellite images provide a good tool to determinate the area, but the thickness can only measured on single points by costly drilling trough the ice. New generation satellites, like the American "Icesat" use RADAR technology to determinate precisely the ice thickness, but snow cover and water are still a problem, and can distort the measurements. After the failure tof the European Space Agency to send a new generation satellite - Cryosat (crashed only few seconds after the start in 2005)- in the orbit, now his brother - Cryosat2- is almost ready.

In December the satellite will leave Munich (Germany) to be transported to the Kazakhstan spaceport Baikonur, from where it will be send in February 2010 with a modified rocket (a former atom weapon carrying Dnepr model) in space.
With a new RADAR-altimeter ("Siral") Cryosat2 will take 20.000 measurements per second in the next three years with an unequalled precision, and be able to determinate changes of thickness in ice of only few centimetres.

Meanwhile reports of Canadian researches under David Barber (University of Manitoba) confirm the receding trend of the ice cover in the Arctic. On 12 September 2009 the ice covered 5,1 million square kilometres, only 2007 and 2008 the area was lesser compared to the mean value of the 30 years of satellite measurements. Compared to the long term observed between 1979 and 2000, the remaining actual ice cover is also 70% of the former area, the area of long lasting ice diminished from 90 to 17%.
Not only the area is declining, also the thickness is inferior, in some areas the thickness diminished from 10m to 2m. The thinner ice is more fragile, and can not resist wave movements or storms.

Biologists are concerned about the status of the polar bear, with a valued population of 25.000 animals: the ice is in vast regions to thin to be used by the animals to hunt, and the sea freeze later in the year.
In the area of Churchill, in the Canadian province of Manitoba ,the biologist Ian Sirling (Canadian Wildlife Service) observed a possible related fact - an increasing of cannibalism events from elder on younger animals.

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