September 25, 2011
NASA ‘May Never Know’ Location of UARS Splashdown
While NASA knows that the remains of the six-ton Upper Atmosphere Research Satellite (UARS) wound up landing somewhere in the Pacific Ocean, the exact location of the spacecraft may never be known, according to a Sunday report by Irene Klotz of Reuters.
The U.S. space agency reported early Saturday morning that the satellite re-entered the planet's atmosphere sometime between 11:23 p.m. EDT on September 23 and 1:09 a.m. EDT on September 24. Much of the UARS would have been burned up upon its return, but an estimated 26 pieces no larger than 330 pounds were believed to have survived re-entry.
"As it fell to Earth, UARS passed from the east coast of Africa over the Indian Ocean, then the Pacific Ocean, across northern Canada and the northern Atlantic Ocean to a point over West Africa," Klotz said. "Most of the transit was over water, with some flight over northern Canada and West Africa."
"Because we don't know where the re-entry point actually was, we don't know where the debris field might be," Nicholas Johnson, chief orbital debris scientist at NASA's Johnson Space Center in Houston, told the Reuters reporter. "We may never know."
Klotz had earlier reported, on Saturday morning, that the satellite might have scattered pieces of debris at locations in Canada. She wrote, "There were reports on Twitter of debris falling over Okotoks, a town south of Calgary in western Canada."
According to the Associated Press (AP), UARS is the largest NASA spacecraft to fall out of orbit and descend uncontrolled back to the planet's surface in over 30 years. The $750 million satellite was originally launched in September 1991, and was scheduled to spend three years measuring Earth's ozone layer, wind, and temperature. It was officially decommissioned in December 2005 after being struck by a small piece of debris.
The re-entry was originally expected to occur sometime in late September or early October, but last week NASA altered their predictions to September 23, plus or minus one day, due to a "sharp increase in solar activity."
Early Friday morning, NASA had reported that UARS would re-enter Earth's atmosphere that afternoon. As a result, it was believed that it would most likely miss North America, as it would not be passing over the continent during at that time.
However, at 10:30 a.m. EDT, they posted an update to the UARS mission page, stating that "the satellite's orientation or configuration apparently has changed, and that is now slowing its descent."
NASA later updated the satellite's status once again, noting that as of 7:00 p.m. EDT, UARS's orbit was 90 miles by 95 miles, and that re-entry was expected to occur between 11 p.m. Friday evening and 3 a.m. Saturday morning. The agency noted that the satellite would be passing over Canada, Africa, Australia, and the Pacific, Atlantic, and Indian Oceans during that time frame.
As previously reported here on RedOrbit, NASA officials believed that the odds of a piece of debris from the UARS satellite would hit a person were approximately 1-in-3,200, and that the odds of any particular individual would be struck were 1-in-21 trillion.
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