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CAPE CANAVERAL, Florida - US and Russian flight controllers worked to fully restore critical computers aboard the International Space Station today after a system crash that could force the US$100 billion ($134 billion) outpost's crew back to Earth.
The US space agency Nasa made plans to keep the visiting space shuttle Atlantis attached to the station for an extra day to help steer the massive complex if the computers, which control navigation, remain a problem.
Flight directors told the crew to cut power to noncritical equipment, such as lighting, to conserve electricity and fuel in case the shuttle's mission to the space station is extended.
"We're just trying to buy some margin for an extra docked day," astronaut Shane Kimbrough from Mission Control in Houston radioed to the crew.
In a worst-case scenario, the computer woes could force the three astronauts aboard the station, including Nasa's newly arrived Clayton Anderson, to leave in the escape ship, a Russian Soyuz capsule.
As a precaution, the Soyuz was put on battery power on Wednesday for seven hours before one primary and one auxiliary computer system in the Russian modules were rebooted early on Thursday, allowing the capsule to be returned to station power.
Two other primary systems, which control navigation and operate life support systems like an oxygen generator and air purifiers, remained shut down.
The station, a project of 16 nations, has backup systems for life support and the shuttle has been firing its control jets to help the space station maintain proper orbit.
"We won't ask you how you're doing because we can imagine," a Russian flight director, speaking through a translator, said to station commander Fyodor Yurckikhin, who skipped a night's sleep to work on the computer problems.
"I hope you haven't run out of steam yet."
Engineers were not sure what was causing the problem with the Russian computers, but the glitches began shortly after a newly installed solar wing panel began producing power.
Nasa plans to fold up the second half of an older solar wing panel that must be moved before the new array can rotate and track the sun for full power.
Spacewalking astronauts Patrick Forrester and Steven Swanson helped guide the old wing into its storage box during an outing on Wednesday. Their crewmates James Reilly and John "Danny" Olivas are due to finish the job during a spacewalk on Friday.
Reilly and Olivas also are scheduled to repair a bit of protruding insulation near the rear of the shuttle. A corner of the blanket tore loose during Atlantis' launch six days ago, potentially exposing inner layers of the shuttle's surface to superheated gases on reentry.
Nasa had already extended Atlantis' mission from 11 to 13 days and added a fourth spacewalk to make sure there was enough time to fix the blanket and retract the old solar wing.
The astronauts must also prepare other station systems for the arrival of new laboratory units and life support equipment for an expanded, six-person resident crew.
The US space agency has three years to finish building the complex before the shuttles, which are the only vehicles capable of hauling major components and assembling the station in orbit, are retired.
The station is a little more than half finished.
- REUTERS
