Sunday 10 November 2013

Doomed European Satellite May Fall to Earth Tonight, But Where?

SPACE.com
Doomed European Satellite May Fall to Earth Tonight, But Where?
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An artist's illustration of the gravity and ocean mapping GOCE spacecraft in Earth orbit. The four-year-old …
A European satellite at the end of its mission is expected to fall out of space tonight. The only question is where its charred and twisted remains may fall.
According to European Space Agency predictions, the falling GOCE satellite could to Earth sometime Sunday night (Nov. 10) or early Monday. The gravity-mapping spacecraft ran out of fuel in mid-October and has been falling back to Earth ever since.
"The satellite is at an altitude of 147 km (91 miles), dropping at a rate of more than 1 km (0.6 miles) an hour," ESA's GOCE spacecraft operations manager Christoph Steiger wrote in a status update today, adding that the atmospheric drag on the satellite is too high to measure. "Given the fast altitude drop and change of environmental conditions, the end of flight operations is getting close."
The GOCE spacecraft is about 17 feet (5.3 meters) long and 3.2 feet (1 m) wide. It weighs about 2,425 pounds (1,100 kilograms). ESA scientists expect 25 to 45 fragments of the satellite to survive the fiery re-entry through Earth's atmosphere. The largest could weigh up to 200 pounds (90 kg), according to The New York Times.
Steiger wrote that temperatures at the nose of the sleek satellite keep increasing, but have not reached levels that would prevent GOCE from functioning.
ESA's GOCE satellite successfully completed its gravity-mapping mission earlier this year, and an uncontrolled fall from space was always to be its fate, ESA officials have said.
The 350 million euro ($467.8 million) GOCE spacecraft launched in March 2009 to measure the Earth's gravitational field with unprecedented detail, according to an ESA fact sheet. The satellite's name is short for Gravity field and steady-state Ocean Circulation Explorer.
The spacecraft was powered by a Xenon ion engine, which allowed it to fly much lower than typical satellites. ESA officials dubbed to satellite the "Ferrari of Space" because of its sleek, fast design. Just after launch, GOCE flew at altitude of 159 miles (255 km) to measure Earth's gravity field and oceans. By August 2012, it had dipped to an altitude of just 139 miles (224 km).
GOCE is the latest satellite to meet its doom with a fiery, uncontrolled plunge from space.
In 1979, NASA's huge Skylab space station fell to Earth and rained debris over parts of Australia. In September 2011, NASA's defunct Upper Atmospheric Research Satellite dropped debris into the Pacific Ocean. One month later, in October 2011, Germany's ROSAT X-ray space observatory burned up in Earth's atmosphere after 21 years in orbit.
In January 2012, Russia's troubled Phobos-Grunt Mars moon probe fell from space after failing to leave Earth orbit following its launch in November 2011.