All eyes to the sky
For America in particular, today will have something of a space theme. The shuttle Atlantis is due to touch down at some time from 2-7pm UK time, and the evening will see a total lunar eclipse – also visible to night owls across the UK from 2-5am (GMT) on Thursday 21 February.
The third celestial event is less routine, and won’t be universally welcomed. In January, the US announced plans to shoot down a spy satellite that it placed into orbit in December 2006, but which never became operational. The satellite, USA 193, is in too low an orbit, and left to its own devices would fall to the earth at some time in early March.
The US says that it must try to shoot down the satellite to prevent a risk from about 400 litres of hydrazine fuel that remains in its fuel tank, but many commentators have questioned the rationale behind the decision, particularly after the US was highly critical of a successful strike by China on one of its own satellites, in January 2007.
Although a successful interception by the US is likely to prevent large items of debris – and military secrets, cynics point out – returning to earth intact, it’s also likely to create a field of smaller debris, not all of which will fall into the atmosphere and be burned up.
Travelling at ‘hypervelocity’, orbital debris can badly damage satellites. A particle striking the space shuttle Endevour in August 2007 holed one of the shuttle’s radiator panels, causing more damage to it than any previous debris strike on them. NASA estimates that the Chinese satellite shoot-down left more than 100,000 items of debris in orbit, according to this CNN article.
The space agency’s quarterly orbital debris report says that 2007 was the worst year ever for orbital debris, and warns that “the consequences will be felt for many, many years to come”.
The latest reports are that the Americans are preparing to take their first shot at USA 193. The US government has warned sailors and aviators to avoid an area of the Pacific west of Hawaii from 3.30 on Thursday morning, UK time – right in the middle of the eclipse, when all eyes will be on the sky.
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Originally posted 2008-02-20 06:57:00. Republished by Blog Post Promoter
