Thursday, April 08, 2010

The European Space Agency's CryoSat-2 Satellite Will Measure the Thickness of Arctic and Antarctic Ice

"Since ice plays a crucial role in moderating Earth's climate and the effects of a changing climate are fast becoming apparent, particularly in the polar regions, it is important to understand exactly how Earth’s ice fields are responding."---"CryoSat: an icy mission," The European Space Agency (ESA)

UPDATE: Today's launch of CryoSat-2 was successful! Check out the updated Guardian (4-8-10) article. Watch the launch replay.

According to the European Space Agency (ESA), "One of the most dramatic signs of climate change is in the extent of Arctic sea ice. Since 2000, the area covered by sea ice in the summer has reduced drastically."

CryoSat is the ESA's mission to measure change in the cryosphere: "the frozen part of the Earth's surface, including the polar ice caps, continental ice sheets, glaciers, sea ice, and permafrost."

A NASA link explains: "[a] mission to measure change in the cryosphere, CryoSat-2 will measure the thickness of sea-ice and the surface elevation of ice sheets in both Northern and Southern hemispheres. For this, it uses an advanced radar altimeter combined with Precise Orbit Determination."

While they are up there, perhaps the ESA might also measure the thickness of the skulls of mendacious global warming denialists, such as Senator Inhofe, 9-11 Truthers, and ignorant bloggers who can only launch lies into cyber-space.

The U.K. Guardian (4-8-10) reports that the CryoSat-2 satellite [Wikipedia] will be launched into space today from the Baikonur Cosmodrome [Wikipedia] in Kazakhstan:

A resurrected satellite, carrying the hopes of climate scientists, will make a second attempt to reach orbit today from the Baikonur cosmodrome in Kazakhstan. The first CryoSat satellite crashed minutes after launch in 2005, ditching - with cruel irony - into the Arctic Ocean it was meant to study.

The €140m (£122m) CryoSat-2 is a replica built by the European Space Agency, but with some additional instruments. If it makes it into orbit, it will be able to measure the thickness of Arctic and Antarctic ice to within a centimetre - an accuracy unmatched until now. Lift-off is being shown live online and is scheduled for 1457 BST.

The melting of sea ice, ice caps and glaciers across the planet is one of the clearest signs of global warming and the UK-led team of scientists will use the data from CryoSat-2 to track how this is affecting ocean currents, sea levels and the overall global climate.

Duncan Wingham, a climate physicist at University College London and the lead scientist for both missions, is hoping this will be second time lucky. "Satellites have transformed our knowledge of what is happening to these distant and uninhabited parts of the planet. CryoSat-2 will help unravel the consequences of the dramatic changes in the poles that we've seen in the past two decades."

Wingham said that, without CryoSat-2, there would be a significant gap in the data needed to track climate change. "The data we do have is patchy because the instrumentation on the earlier generation of satellites was not designed to deal with the ice-sheets," said Wingham.

The first CryoSat mission was launched from the Plesetsk cosmodrome in northern Russia on 8 October 2005, but it crashed into the icy sea shortly afterwards, due to a malfunction in the launch vehicle.

Approval for a successor mission to CryoSat was given by Esa within months of the accident. The new probe was built using improved electronics and batteries, and an extra radar altimeter, a device that will fire microwaves at the Arctic and Antarctic ice to reveal its thickness.

Scientists have already shown that the amount of sea ice in the Arctic is falling, and the latest data confirms the long-term trend. But some data also suggests that the ice that remains is thinning. If the measurements from CryoSat-2 bear out this thinning theory, it would mean the ice is being lost more quickly. Scientists are concerned that the loss of sea ice is leading to a feedback effect where the newly exposed, darker ocean absorbs more sunlight, warming the water yet further. In addition, sea ice can block glaciers on land from falling into the ocean, so its loss could raise sea levels.

"We are altering the Arctic climate far faster than anywhere else on Earth," said Wingham. "We're changing the whole structure of the Arctic Ocean, but we still don't know what the consequences will be. We have to find out what is going on up there. CryoSat-2 will do that."

Another antenna on CryoSat-2 will measure the shape of the ice and tell researchers about slopes and ridges at the edges of the great Antarctic and Greenland ice sheets.

Alan O'Neill, director of the National Centre for Earth Observation at the University of Reading said: "These measurements are absolutely crucial to our understanding of climate variability and climate change. Not only are they early indicators of climate change because of feedbacks in the system. But they're not remote from what affects people's lives and the weather that affects the rest of the planet. The polar regions are connected to the rest of the planet by the atmosphere and the ocean." [See the full text.]

The ESA has a site where people can watch the launch live. Check out their latest updates, too. They also have interesting articles such as Earth's Changing Ice" and "Protecting the Environment." Here is the Wikipedia entry for the ESA.

The live launch site observes:

CryoSat, ESA's ice mission, is scheduled for launch today at 15:57 CEST (13:57 UT). Live web streaming starts at 15:35 CEST (13:35 UT).

CryoSat-2 will be placed into orbit 700 km above the Earth by a Russian Dnepr rocket launched from the Baikonur Cosmodrome in Kazakhstan. The launch operator is Kosmotras.

CryoSat will be the third of ESA’s Earth Explorer satellites in orbit, following the launches of GOCE (in March 2009) and SMOS (in November 2009).

The 700 kg CryoSat spacecraft – whose name comes from the Greek kryos meaning cold or ice – carries the first all-weather microwave radar altimeter. The instrument has been optimised for determining changes in the thickness of both floating sea ice, which can be up to several metres, and polar land ice sheets, which in Antarctica can be close to 5 km thick. The mission will deliver data on the rate of change of the ice thickness accurate to within one centimetre.

The BBC (4-8-10) also has an interesting article that includes graphics and video about the CryoSat program:

"One will be nervous," said Richard Francis, the Esa Cryosat project manager.

"But it will be so exhilarating when the spacecraft finally makes it into orbit and we get the first contact with it, the thing we didn't get the last time."

Although built mainly in Germany and France, CryoSat-2 is led scientifically from the UK by its proposer and principal investigator, Professor Duncan Wingham from University College London.

The spacecraft will measure very precisely the rates of change of sea and land ice in the Arctic and the Antarctic.

A key quest for Cryosat will be to assess the volume of sea ice in the Arctic - something that has been hard to do from space.

Satellites have long been used to track ice extent (area), but calculating the thickness of the marine floes requires the overflying spacecraft to gauge the difference between the top of the ice surface and the top of the water - a relatively simple calculation then gives the overall volume.


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