The astronauts aboard the International Space Station briefly evacuated to a Russian escape spaceship today when a piece of space debris came too close, Nasa said.
The debris was an old motor that probably was once a part of the space station, Nasa spokeswoman Laura Rochon said.
The Russian Space Command said the debris had passed the station and the crew were in no danger and had returned.
The current crew of the space station includes U.S. astronauts Michael Fincke and Sandra Magnus and Russian Yury Lonchakov. The station has been continuously manned since November 2000.
Space junk is considered a threat to the 800 or so commercial and military satellites estimated to be operating in space as well as to the International Space Station. There are more than 18,000 pieces of debris catalogued.
Russian mission control said that the evacuation lasted only about 10 minutes.
"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 by telephone.
"They didn't even close the hatch between the station and the Soyuz and sat there for only about ten minutes. We do not know where the space debris was from," he said.
The incident comes after Nasa postponed until Sunday yesterday's scheduled launch of the space shuttle Discovery on a mission to the space station. The US space agency blamed a hydrogen leak during fueling for the postponement.
The purpose of the shuttle flight - the first of five planned for this year - is to deliver a final set of solar power panels to the space station and transport Japan's first astronaut to serve as a member of the live-aboard station crew.
Sunday's lift-off was scheduled for 7:43 p.m. (2343 GMT) from the Kennedy Space Center in Florida.