The main control computers on board the International Space Station that suffered a general malfunction and shutdown last week have not yet been fully repaired, but officials announced some relief, since they found that the four of the six computers were successfully restarted and remained stable overnight.

A malfunction caused the shutdown of two key computers that control navigation and oxygen production on the Russian side of the International Space Station. Later, all six main control computers reported a glitch that forced astronauts on Thursday to turn off equipment in the docked shuttle Atlantis to conserve energy.

It seems that some form of event external to the computers, outside their design envelope, might have caused them to crash at some point during the recent ISS power reconfiguration, so it was not really a hardware of software glitch, as initially suspected.

The conclusion of the analysis supports the manufacturing company, EADS, that supplied the computers to the Russian side of the station in return for Russian docking systems to be used with ESA's Automated Transfer Vehicle (ATV), a supply craft for the International Space Station (ISS), scheduled to launch next year in January.

The successful restart was performed after the ISS crew made a local harness change to bridge a protection circuit, last night, that allowed them to partially restore power to four of the six control computers, without which the station could not be maneuvered in space. Moreover, the operating software has been reloaded and the Russian subsystems are gradually being brought back on line.

It looks like not all the machines are damaged to the point of inoperability but the exact cause of the malfunction remains unknown, as scientists from Astrium and the Russian space agency are working around the clock to solve the problem, which could lead to an extension of the stay aboard the station for the three permanent residents.