* Astronomy

Arctic explorer delivers unique snow-depth data for CryoSat
Following a formidable 106-day trek across the Arctic, which ended with the two Arctic Arc expedition members relying on Envisat images to guide them safely through disintegrating sea-ice, intrepid polar explorer Alain Hubert recently visited ESA to handover a unique set of snow-depth measurements.

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Scientists and polar explorers brave the elements in support of CryoSat-2
It is perhaps an unlikely combination an international team of scientists stationed in Svalbard, Norway and two polar explorers crossing the North Pole on foot. Both teams, however, are currently part of a common effort to collect vital data on the ground and from the air in support of ESA's ice mission CryoSat-2.
 The CryoSat-2 mission, due for launch in 2009, will provide highly accurate information on changing marine and land ice thicknesses over the entire north and south polar regions, and in doing so will help address key questions regarding the impact of climate change on the polar environment. The mission is a technical tour-de-force if you take a step back and consider that the satellite will be travelling at over 23,000 kilometres per hour at 717 kilometres above the surface of the Earth and yet still measure changes in the ice thickness down to a few centimetres per year using its sophisticated radar altimeter SIRAL. Given these objectives and the importance of accurate measurements in assessing environmental change, it is not surprising that ESA goes to great lengths to ensure that the data from CryoSat-2 will be as accurate as possible.  
Enter the Arctic Arc Expedition, part of the International Polar Year. The expeditions two Belgian explorers, Alain Hubert and Dixie Dansercoer, 'stepped' onto the sea ice off the coast of Siberia on the 1 March 2007 and have so far covered a staggering 2,500 km each pulling a 130-kg sledge holding supplies and equipment. Along the way these two intrepid explorers are contributing to the preparation of the CryoSat-2 mission by measuring snow depths at regular intervals. These data in turn will be used by scientists to assess how well snow conditions can be predicted using existing climate models as well as inputs to methods for improving the accuracy of CryoSat-2 maps of sea-ice thickness.

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The European Space Agency has announced that it would proceed with the development and launch of the CryoSat-2 earth sciences satellite that will replace one lost in a launch failure last year.

"This decision is very important, as the scientific community in Europe and elsewhere is eagerly awaiting resumption of the CryoSat mission. We are happy to have obtained approval today" - Volker Liebig, ESA Director of Earth observation programmes.

The satellite will measure the thickness of polar ice as a means of studying global climate change. the spacecraft will be similar to the original CryoSat, but will cost less — €106.4 million versus €140 million — by taking advantage of enhanced satellite operations and data processing capabilities.
The launch of the original CryoSat spacecraft was unfortunately aborted on 8 October 2005 due to a malfunction of its Rockot launcher, which resulted in the total loss of the spacecraft.
CryoSat-2 is scheduled for launch in March 2009.

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Prof Duncan Wingham , the UK scientist behind the lost Cryosat probe is to learn on Friday whether his mission will be re-built.

He proposed and masterminded the multi-million-pound satellite, which fell into the Arctic Ocean last year when its rocket failed.
The European Space Agency (Esa) is expected to approve "Cryosat 2" at high level talks in Italy, amid calls from the worldwide scientific community.

The new craft will study how polar ice is responding to climate change.
Previous data suggests the Earth's ice sheets are thinning in some areas, particularly in the Arctic Ocean where the extent of summer ice reached a record minimum last year.

Professor Duncan Wingham of University College London proposed the Cryosat mission in 1998 to answer many of the uncertainties in climate science.
Space officials say a "clone" will be cheaper than the original £90m (135m euro) mission, and could be launched in three years.
Jean-Jacques Dordain, director-general of Esa, has said several times that the importance of the Cryosat mission warrants a re-launch. And European ministers agreed in December that it was a priority.
But the final decision rests with members of Esa's Earth Observation Programme Board who meet on Thursday and Friday at Esa's research centre, Esrin, in Frascati near Rome.

Source BBC