Image caption The ISS currently has a six-person crew

Nasa ground controllers have re-established contact with the International Space Station less than three hours after a computer failure briefly interrupted communication.

Flight controllers in Houston were updating software on the ISS when one of its data relay systems broke down.

The ISS had been able to make contact intermittently via Russian stations.

Nasa normally speaks and sends data to the station from Houston, via three communications satellites.

Interruptions in both communication and control have happened a few times in the past, the space agency said.

The primary computer that controls critical station functions defaulted to a backup computer, but it was not letting the station communicate with Nasa's Tracking and Data Relay Satellites, the US space agency said.

The problem occurred at about 09:45 EST (14:45 GMT).

'Not terrible'

The ISS marked its 10th anniversary of continuous human occupation on 2 November 2010. Since Expedition 1 in 2000, the space station has been visited by 204 astronauts.

The current crew is made up six men: two Americans, three Russians and a Canadian.

Former astronaut Jerry Linenger, who was aboard the Russian space station Mir during a dangerous fire in 1997, told the Associated Press news agency that a loss of communication with the ground "is not a terrible thing" as long as there is no crisis going on.

"You feel pretty confident up there that you can handle it," he said. "You're flying the spacecraft.''

In the past few weeks the space station has been purposely simulating communications delays and downtimes to see how the crew on a future Mars mission would handle the interruptions, NASA spokesman Josh Byerly said.

Tuesday's loss of communication was not part of those tests, but may prove useful, he added.