The crew of the International Space Station rode out a threat of collision with a debris cloud in a Soyuz space capsule.
An unusually close encounter highlighted the dangers of a growing junk pile in space.
“The debris threat to the International Space Station has passed,” NASA said in a statement.
The scare arose when the three member crew learned too late to take evasive action of an approaching a debris cloud that exposed the space station to a risk of a potentially catastrophic collision.
NASA appeared most concerned about a piece of a satellite motor that was close enough that the space station would ordinarily undertake an evasive manoeuvre, NASA said.
Laura Rochon, a NASA spokeswoman at the Kennedy Space Centre in Florida, had said the risk of collision was “very low”.
“The piece itself is about one third of an inch and it\’s about 4.5 kilometres away,” she said.
But Mike Fincke, the mission commander, Yuri Lonchakov, the number one flight engineer, and Sandy Magnus, the number two flight engineer, exited the space craft and battened themselves in the Soyuz spacecraft.
NASA said the move was a precaution in case the crew needed to detach from the space station.
The all-clear was sounded about 10 minutes after the crew entered the capsule.
The US Strategic Command notified NASA of the debris field late Wednesday, but NASA said it was too late for flight controllers to coordinate a “debris avoidance” manoeuvre.
“Every once in a while, the crew has to do orbital debris avoidance manoeuvres but this time they didn\’t do that because we have an upcoming launch possibly on Sunday and they need to stay at the same altitude,” Rochon said.
The US Joint Space Operations Centre tracks about 18,000 objects in orbit, so many that it has to decide which to follow most closely, like those that might fly by the International Space Station or manned space flights.
Experts estimate that there are more than 300,000 orbital objects measuring between 1cm 10cm in diameter and “billions” of smaller pieces.
Travelling at speeds of up to thousands of kilometres an hour they pose a risk of catastrophic damage to spacecraft.
Last month, a spent Russian satellite collided with an Iridium communications satellite, showering more debris in an orbit 436km above the space station.
US military trackers failed to anticipate that collision, the first between two intact satellites, the Pentagon said at the time.