Mon, Oct 24, 2011 - Page 6 News List

Location of debris from satellite unknown


Scientists were trying to establish how and where a defunct German research satellite returned to the Earth yesterday, after warning that some parts might survive re-entry and crash at up to 450kph.

There was no immediate solid evidence to determine above which continent or country the ROSAT scientific research satellite had entered the atmosphere early yesterday, said Andreas Schuetz, spokesman for the German Aerospace Center.

Most parts of the minivan-sized satellite were expected to burn up, but up to 30 fragments weighing a total of 1.7 tonnes could crash.

Scientists were no longer able to communicate with the dead satellite and it must have traveled about 20,000km in the final 30 minutes before entering the atmosphere, Schuetz said.

Schuetz said it could take days to determine exactly where pieces of the satellite had fallen, but that the agency had not received any reports that it had hit any populated areas.

“We have no such information,” he said.

Scientists said hours before the re-entry into the atmosphere that the satellite was not expected to hit over Europe, Africa or Australia. According to a precalculated path, it could have been above Asia, possibly China, at the time of its re-entry, but Schuetz said he could not confirm that.

The 2.4 tonne scientific ROSAT satellite was launched in 1990 and retired in 1999 after being used for research on black holes and neutron stars and performing the first all-sky survey of X-ray sources with an imaging telescope.

The largest single fragment of ROSAT that could hit into the earth is the telescope’s heat-resistant mirror.

During its mission, the satellite orbited about 600km above the Earth’s surface, but since its decommissioning it has lost altitude, circling at a distance of only 330km above ground in June for example, the agency said.

Even in the last days, the satellite still circled the planet every 90 minutes, making it hard to predict where on Earth it would eventually come down.

A dead NASA satellite fell into the southern Pacific Ocean last month, causing no damage, despite fears it would hit a populated area and cause damage or kill people.

Experts believe about two-dozen metal pieces from the bus-sized satellite fell over a 800km span.

The German space agency puts the odds of somebody somewhere on Earth being hurt by its satellite at one in 2,000 — a slightly higher level of risk than was calculated for the NASA satellite. However, any one individual’s odds of being struck are one in 14 trillion, given there are 7 billion people on the planet.

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