Minutes between China and falling space junk disaster

Published on Wednesday 1 February 2012 00:00

SEVEN short minutes saved Beijing from impact last year when a German satellite spun out of its orbit and began hurtling towards Earth, it has been revealed.

Germany’s research satellite Rosat plunged into the Bay of Bengal on October 2011, two decades after launch, but it came perilously close to hitting the Chinese capital.

Rosat went aloft on June 1, 1990, launched into orbit from Cape Canaveral on a quest to search for the sources of X-ray radiation in space. It was a mission intended to last 18 months – but the satellite remained transmitting data about black holes and far-off galaxies for nine years.

It began falling towards Earth after a further redundant 11 years on October 22 last year and came “perilously close” – in the words of European Space Agency scientists – to hitting Beijing at nearly 300 mph.

“Beijing lay directly in the path of its last orbit,” said Manfred Warhaut of the European Space Operations Centre in Darmstadt, Germany.

An impact “was very much within the realm of possibility,” added Heiner Klinkrad, head of the ESA’s space debris team.

Rosat weighed 2.5 tons. Normally, some 20 to 40 per cent of a satellite reaches the Earth’s surface when it falls out of orbit. “But with Rosat, we knew it would be around 60 per cent because it was made out of particularly heavy and durable parts,” said Mr Klinkrad.

Parts of the satellite would likely have torn deep craters into the city, may have destroyed buildings and almost certainly would have resulted in human casualties. Scientists had no way of controlling it once it went out of commission miles above the Earth.

Rosat was one of the closest runs yet involving “space junk” returning to Earth. “Our calculations showed that, if Rosat had crashed to the ground just seven to ten minutes later, it would have hit Beijing,” said Mr Klinkrad.

Next on the crash list is the Nasa Rossi X-ray Timing Explorer, which will present a 1-in-1,000 chance of harming someone when it makes an uncontrolled fall from Earth orbit some time after 2014 – a level ten times riskier than Nasa now requires for re-entering spacecraft, according to an agency spokesman. The forecast for the satellite’s re-entry frames a return between 2014 and 2023. Fluctuations in solar activity cause the atmosphere to expand and contract, making it difficult to predict when uncontrolled satellites will re-enter the Earth’s atmosphere.

The satellite, launched in December 1995, was designed before Nasa issued standards for safety from re-entering spacecraft. Nasa satellites must now have a probability of striking a person of less than 1-in-10,000.

“This satellite was launched four months before the first Nasa standard on orbital debris mitigation and re-entry risk management was issued,” said Beth Dickey, a spokeswoman at Nasa in Washington, DC.

“As such, it was not subject to the re-entry risk guideline, since it had already been built.”

The Russian space probe Phobos-Grunt, which was also mounting a Chinese orbiter to Mars, crashed back to Earth on 15 January due to an as-yet unspecified technical problem. It fell into the eastern Pacific Ocean. Had it remained aloft for just a few more minutes, it would have crashed into South America.

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JimA3220

Friday, February 3, 2012 at 09:17 PM

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GibsonNSW

Thursday, February 2, 2012 at 08:02 AM

Old Postie is a stayer. He appears on the Washington Post as well.

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postmark54

Wednesday, February 1, 2012 at 08:28 AM

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JimA3220

Wednesday, February 1, 2012 at 02:09 AM

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Iran Gets US Drone

Wednesday, February 1, 2012 at 01:26 AM

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Wednesday, February 1, 2012 at 12:56 AM

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