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Space Station gets high tech broom

A laser 'broom' intended to clear space junk out of the orbit path of the International Space Station, will be tested on a space shuttle mission in 2003.

According to this week's New Scientist, the high-tech broom, known as Project Orion, will cost $200 million.

"With a laser system we could clear from orbit all the debris between 1 and 10 centimetres in size within two years," says Jonathan Campbell of the Marshall Space Flight Centre in Alabama who leads Project Orion.

While the space station has a shield that protects it from impacts with objects smaller than 1 centimetre across, and space debris larger than 10 centimetres can be seen and avoided, intermediate objects are a problem.

NASA engineers believe that impacts with intermediate objects will generate a shower of particles, several of which could penetrate the hull.

"The result could be much worse, like the difference between a single bullet and a shotgun blast," says Campbell.

Reports from the International Astronomical Union estimate that there are 2,000 tons of material in low Earth orbit and that the Earth is currently circled by more than 100,000 objects larger than 1 centimetre.

Campbell's team has been measuring the forces that megawatt laser pulses can exert on debris and has shown that a laser broom could slow down and deflect debris from the path of the spaceship.

The next stage, he says, is to test whether debris of this size can be spotted and tracked from the ground. The shuttle will release simulated space debris equipped with GPS so that its position can be monitored. Then a ground-based laser will "light up" the target.

While joint funders of the tests, NASA and the US Air Force, are keen not to breach international treaties preventing the use of laser weapons in space, and Project Orion is only designed to test the ability of the laser to lock onto space junk, some may still suspect the technology of being linked with missile defence projects.

"There's certainly a track record of space debris being used as a cover story for missile defence projects," says John Pike, a policy analyst at the Federation of American Scientists in Washington DC. "I have no doubt that the NASA project is innocent but other countries have plenty of reasons to be suspicious."