Nasa says its six-tonne UARS satellite plunged to Earth over the Pacific Ocean

NASA--Nasa says its six-tonne UARS satellite plunged to Earth over the Pacific Ocean, off the US west coast.
It appears likely the decommissioned craft came down between 03:23 and 05:09 GMT - with a best estimate of 04:16.
If correct, this means any debris that survived to the surface probably went into water and not on land.
The Upper Atmosphere Research Satellite (UARS) is the largest American space agency satellite to return uncontrolled into the atmosphere in about 30 years.
The fall to Earth was monitored by the Joint Space Operations Center (JSPOC) at Vandenberg Air Force Base in California. Its best estimate for the timing of the re-entry would have seen UARS come in at a point located at 31 degrees North latitude and 219 degrees East longitude - well out into the North Pacific.
However, if UARS re-entered many minutes after 04:16, it is possible debris could have reached the American landmass.
There were some unconfirmed reports of glowing wreckage moving across the sky in western Canada, but Nasa said it had yet to receive credible evidence that this was so, less still that any debris items had been found.

"I've got no reports that I've seen that talk about people who think they might have recovered debris," Nick Johnson, Nasa's chief scientist for orbital debris at the Johnson Space Center in Houston, told reporters during a media teleconference.
"Obviously, we're going to continue to keep our eyes and ears open, and if we receive any reports like that we'll try to go verify."
Most of the 20-year-old satellite should simply have burnt up on re-entry into the Earth's atmosphere, but modelling work indicated perhaps 500kg could have survived to the surface.
Calculations estimated this material would have been scattered over an 800km path. Nonetheless, with more than 70% of the Earth's surface covered by water, many experts had offered the view in recent weeks that an ocean grave was going to be the most probable outcome for UARS.
"Because we don't know where the re-entry point actually was, we don't know where the debris field might be. If the re-entry point was at the time that JSPOC has its best guess of 04:16 GMT then all that debris wound up in the Pacific Ocean," Nick Johnson reiterated.
UARS was deployed in 1991 from the space shuttle Discovery on a mission to study the Earth's upper atmosphere.
It contributed important new understanding on subjects such as the chemistry of the protective ozone layer and the cooling effect volcanoes can exert on the global climate.      Source: bbc.co.uk

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