The International Space Station partly restored from the computers breakdown on Thursday, according to NASA mission control center.

The failure of Russian navigation computers, which provide backup attitude control and orbital altitude adjustments, may force NASA extend Atlantis mission by an extra day to give engineers more time to figure out the problem.

The worst scenario is that the station's three crew members might have to return to Earth early if the computers are not fixed.

However, "we're still a long way from where we would have to de- man the space station," said Bill Gerstenmaier, NASA's associate administrator for space operations.

Russian engineers has re-established part of the communications, and they continued efforts with U.S. experts to bring the computers back up to full operation.

For now, the station's control moment gyroscope are handling attitude control, with the shuttle's propulsion system providing backup.

The Atlantis mission had already been extended from 11 to 13 days to repair a thermal blanket that peeled during launch.