First satellite collision produces dangerous wreckage
Joe Byrne
Published: Wednesday February 11, 2009

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Outer space is getting too crowded already.

A satellite crash that occurred on Tuesday was the first of its kind, NASA reported Wednesday. Two communications satellites, a privately owned US machine and a presumably defunct Russian Cosmos orbiter, collided over northern Siberia around noon ET. As more and more devices are put into orbit around Earth to replace first-generation space equipment, the likelihood of satellite crashes causing expensive damage is increasing rapidly. Scientists have been warning of the danger of crowded orbits for years, but the solutions are lacking.

The Space Surveillance Network, run by the US military, currently tracks 8,000 space objects in Earth's orbit. Of these 8,000, approximately 560 are operational satellites. The rest are rocket debris and non-operational satellites. The objects are regularly observed by the military in the Space Catalog.

But though the tracking of satellites is extensive, our ability to do anything about an imminent crash is limited by distance. Satellites passively orbiting the planet have little to stop them, and if the military can calculate a crash in the near future, the most that can be done is a warning.

The crash between the Iridium Corporation's satellite and the Cosmos orbiter resulted in 500 to 600 new pieces of debris going in every direction, crossing the orbits of other satellites. Nicholas Johnson of NASA reported to Reuters, "It takes a while for the debris to spread out and for us to get an accurate head count."

The only manned object constantly in orbit is the International Space Station, at an altitude of 218 miles above Earth. The speed at which a satellite travels means that debris is flung far and wide. Tuesday's collision occurred at 490 miles; Johnson told the New York Times today that he believes there are already objects from the collision that have passed through space station altitude. Though the risk to the station - which currently has 3 astronauts on board - is very small, the risk increases exponentially with every satellite collision that occurs. Each crash results in hundreds of new fragments with their own individual orbits. And though low-orbit communications satellites eventually burn up in Earth's atmosphere after they are no longer useful, high-orbit satellites remain as long as they aren't dismantled or obliterated.

For now, all we can do is keep watching.