Chinese Test Anti-Satellite Weapon

[BGonaSTICK]

Millions of new pieces of space junk may have been generated during a Chinese test of an anti-satellite weapon last week, US officials worry.

The debris could be dangerous for existing satellites - and even for astronauts aboard the International Space Station and the space shuttle - for years to come.

On 11 January, China launched a missile from or near the Xichang Space Centre in the southwestern province of Sichuan. This likely released a projectile that slammed into one of its derelict polar-orbiting weather satellites, known as Feng Yun 1C, which flew at an altitude of about 800 kilometres.

The collision created about 40,000 pieces of debris larger than 1 centimetre, estimates David Wright, co-director of the global security programme at the Union of Concerned Scientists in Cambridge, Massachusetts, US.

That will nearly double the amount of debris of that size at similar altitudes, he told New Scientist. It may also have created 2 million fragments wider than 1 millimetre across.

Such altitudes are heavily trafficked by imaging, meteorological, surveillance, remote-sensing and communications satellites. These spacecraft could be seriously damaged if they were hit by the debris, which can travel at 7.5 kilometres per second – 30 times faster than a jet aircraft.

"Small things can cause very big problems," US State Department spokesman Tom Casey said in comments about the Chinese test.

Because the density of the atmosphere is low at altitudes of about 800 km, the space junk could circle the Earth for a decade or more without dropping down low enough to burn up in the atmosphere.

And if at some point the debris did hit a satellite, that satellite could also break up, creating ever more space junk in a cascade effect.

"It's certainly an irresponsible move by the Chinese government to deliberately destroy a satellite in a heavily used orbit and to create mass quantities of space debris," Theresa Hitchens, director of the Center for Defense Information in Washington, DC, told Agence France-Presse. "They are endangering a number of people's satellites."

Bart Gordon, chairman of the US House Science Committee, said the test was "ill-advised" because of the risk to civil and commercial satellites and "fosters an environment that will make it more difficult to consider potential cooperation with China in civil space activities".

News of the test comes just as NASA announced that eight spacecraft and rocket stages accidentally broke up between May and December 2006, adding to the already crowded shell of space junk surrounding the Earth.

"There is certainly a concern that if people continue with business as usual, you would get to the point where the risk to your satellite is much higher than it is now," Wright told New Scientist.

The US uses radar to track space debris larger than 10 cm across, so it will be scanning the skies to evaluate the risks of the test to existing spacecraft.

Source: New Scientist (_http://space.newscientist.com/article.ns?id=dn10999)

[Jimdefruit]

If I am right, and I think I am, any change in velocity of a particle will cause it to increase or decrease its orbital height. If it stays in the same orbit it will be stationary relative to other sateliite objects. The dangerous particles will be those that were blasted to a higher orbit but with incorrect velocity such that they will oscillate for a while passing through the line of the normal orbits.

40,000 bits? I would be interested to know how that was calculated.

[BGonaSTICK]

They probably counted the bits from when they nuked, err, I mean 'accidentally broke up' eight spacecraft and rocket stages between May and December 2006.

Whatever's going on, it's another whole load of crap floating around in space.