Junk alert for space station crew

The crew had to move into the Russian Soyuz capsule

The crew of the International Space Station have been forced to shelter in the Russian Soyuz capsule after a close call with a piece of space debris.

The crew are now out of danger and have returned to the ISS, Russian mission control officials told the Reuters news agency.

Nasa said news of the debris threat had come too late for flight controllers to move the space station out of the way.

The scare comes just over a month after two satellites collided over Siberia.

Officials said the decision to move the astronauts had been a precaution and that the probability of an impact with the ISS had been low.

The space station's operating rules require crew members to be evacuated when debris is detected within a set distance.

But Russian Yury Lonchakov and Americans Michael Fincke and Sandra Magnus took refuge for 11 minutes in the Soyuz escape capsule.

Tiny fragment

The debris was about one-third of an inch (1cm) in size and part of an old "payload assist motor" that was previously on either a Delta rocket or on the space shuttle, Nasa spokeswoman Laura Rochon told journalists.

Objects in orbit travel at tens of thousands of kilometres per hour. At these speeds, even a small piece of debris can knock out a satellite or, potentially, cause serious damage to the space station.

"The crew have returned to the station. They are in absolutely no danger and the debris has already passed by the station," a spokesman for Russia's mission control said.

"They didn't even close the hatch between the station and the Soyuz."

Experts recognise a growing threat to spacecraft from orbital debris and several events over the past three years have drawn attention to the problem.

On 10 February, the US Iridium 33 communications satellite collided with Cosmos 2251, a retired Russian intelligence comms sat.

The chances of such an event had been estimated at millions or billions to one. The impact produced two expanding clouds of debris in intersecting orbits.

In January 2007, China caused international alarm when it destroyed one of its defunct satellites in a missile test. The US military estimates that this event created 2,500 new pieces of debris in orbit.