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5 December 2013 11:26 am ,
Vol. 342 ,
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Researchers Unable to Revive Europe's Envisat
23 April 2012 12:53 pm
Things are not looking good for Europe's flagship Earth observation satellite Envisat. Ground controllers lost contact with the craft on 8 April and so far have been unable to re-establish contact. Envisat, the largest ever civilian Earth observing satellite, carries a battery of sensors for scanning land, sea, and atmosphere, and has been the mainstay of European environmental researchers for the past 10 years.
Following the loss of contact, controllers have aimed a laser at retroreflectors on the craft and found that it is still in a stable orbit and not spinning; that rules out a collision. Images from a ground-based radar show that the craft's own radar antenna and solar array are both intact. On 15 April, the French Space Agency spun round its recently-launched Pleiades Earth observation satellite to point upward and snap an even more detailed picture of Envisat from just 100 kilometers away. This again showed no sign of damage and gave no clues to what is wrong.
The European Space Agency (ESA) had hoped that Envisat would last another couple of years until it launches its next-generation Sentinel satellites, starting next year. In the meantime, researchers must find other sources of data. ESA already has an agreement to get radar imaging data from Canada's Radarsat. Those using Envisat's radar altimeter also have alternatives. "We at least for the time being have [ESA's] CryoSat-2 to ensure continuity of polar altimetry," says climate physicist Seymour Laxon of University College London. But for those studying air quality and atmospheric science, "there is nothing to replace [Envisat's instruments]," says Robert Meisner of ESA's Earth observation program. The next generation of these instruments are due to fly on Sentinel 3, slated for launch in 2014.
"Envisat was a big success. We celebrated its tenth birthday just a few weeks ago. We're disappointed that it's just gone," says Meisner. Ground controllers are continuing to try different ways to re-establish contact and are not saying how long it will be before they give up. If the mission has to be abandoned, Meisner says the craft is in a stable orbit and is unlikely to re-enter the atmosphere for 100 years.