Computers go down on space station -

The International Space Station has been walloped by a number of computer errors which have caused communications to fade in and out.

Mission control says that three command and control computers seem to be working, engineers do not yet understand what has caused the machines to repeatedly transition flit from one to the other.

The problem appears to have been caused by command and control software, updated before the shuttle Endeavour's flight to account for a new ironically named Tranquility module.

Computers in Tranquility also have problems and it is not clear if they are related to the command and control issues.

When things are going well the station has three command and control computers. One operates as the prime machine sending commands to various systems and providing critical telemetry.

A second C&C computer operates in backup mode, ready to take over if the prime computer suffers a problem, and the third machine operates in standby in case the other two pack a sad.

However, on Sunday, the prime computer refused to get out of bed, and the second one kicked in. It failed a diagnostic and went to the equivalent of a blue screen of death.

The third one kicked in and was running for an hour and then it gave up the ghost. Then the first one rebooted and it is working ok again.

While it was mucking around communications were lost for a while.

Space station commander Jeff Williams indicated there were a few problems with the computers later yesterday. This time only the backup and standby computers were stuffed up.

Houston thinks that its boffins have found a fault in a computer system in the Tranquility module, but it was not immediately known if that was related to the C&C problem. Astronauts are apparently checking to see what they have on board which can be used to do a bodge job.