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US: Satellite collision poses 'small' risk to ISS: NASA

13 Feb 2009 3:06 AM

WASHINGTON, Feb 12 AFP - An unprecedented collision between a Russian and a US satellite poses an "elevated" but "very small" risk to the International Space Station, the US space agency said Thursday.

"So far, NASA experts have determined that the risk to the space station is elevated. They estimate the risk to be very small and within acceptable limits," NASA spokesman John Yembrick told AFP.

"NASA's Earth-observing satellites orbit at an altitude of approximately 707km, which is not far from the 790km altitude of the collision. They are of the highest concern as NASA learns more about the newly created debris field."

A disused Russian military satellite, Cosmos 2251, collided on Tuesday at 1655 GMT (0355 AEDT) with a US communications satellite owned by the Iridium company, at approximately 790km above Siberia, NASA indicated.

The agency said the magnitude of the two large debris clouds from the collision would not be known for at least several weeks.

The ISS and its three crew fly about 354km above the Earth, far below the point of the collision. But NASA's Earth observation satellites and the Hubble Space Telescope travel at higher orbits and are thus at greater risk of damage.

"We are looking at around more than 500 pieces of debris," said Navy Lieutenant Charlie Drey, a spokesman with US Strategic Command (STRATCOM).

"Anytime you have something like this happen, there is a concern about other objects that are in orbit. Now that you have all this debris there, it does pose a risk to satellites," he told AFP.

NASA's space shuttle Discovery is to launch from Florida's Kennedy Space Center on February 22 at the earliest, on a mission to the ISS. "At this time, there is no danger to the scheduled launch," William Jeffs, a NASA spokesman based at the Johnson Space Center in Houston, Texas, told AFP.