Russian engineers working with crashing computers aboard the International Space Station were not able to bring them back into full working order overnight, a NASA mission manager said on Friday.
Holly Ridings, the space station flight director, said that during an overnight attempt by the engineers to bring the balky computers up, they were able to power up the computers and get what she called a "heartbeat" from one to allow communications. However, the engineers "were unable to communicate with it properly," she said in an interview on NASA TV, and "they decided they would turn the power back off again" to the computers.
NASA officials said on Thursday that they fully expected engineers to resolve the unprecedented failure of computers on the International Space Station, though they cautioned that the process could take days.
“Don’t get up tomorrow and expect it all to be working,” said Michael T Suffredini, the space station program manager, at an evening briefing for reporters on Thursday. But he added, “I feel like we’re making good progress to resolving this issue.”
The Russian computers —which were actually built in Germany by Daimler-Benz —began crashing on Tuesday as astronauts were connecting a new truss and solar arrays to the station.
In the two-pronged system for maintaining the orientation of the $100 billion station as it circles the Earth, the American component runs gyroscopes that provide stability, and the Russian system controls thrusters that take over when the gyroscopes are overwhelmed.
The Russian system is also used to shif station orientation for operations like docking. Thruster control was passed to the shuttle Atlantis, which has enough fuel to adjust the station’s positioning for several days.

Return
The shuttle is scheduled to return to Earth next week. The mission has already been extended by two days to perform a fourth spacewalk, and may be extended further to deal with the computer issue, officials said.
If the computer problem is not corrected, the station could be unable to maintain the best position for charging its solar arrays, and in the worst case, NASA and the Russian space agency would have to evacuate the station.
‘Noise’
The leading theory of what went wrong, Mr. Suffredini said, was “noise” in the electrical system that may have been introduced with the newly installed wiring. The Russian computers, which were made in Germany, are sensitive to line noise. Engineers will try to isolate those computers from the new wiring, he said.
But that was precisely what the astronauts tried overnight, and the computers did not come up successfully, Ms Ridings said. Attempts to isolate the system by "de-mating" electrical connectors to the new power arrays —basically, pulling the plug — did not bring the three navigation computers, which back each other up and are referred to as "Lanes," back into full working order.
Ms Ridings said that astronauts monitored the electrical lines with an oscilloscope to look for evidence that the lines were noisy and shared the readings with engineers on the ground, but "nothing jumped out at them," she said. "It would have been nice to see a smoking gun, but that’s not always the way these things work." The Russian cosmonauts aboard the station have been taken off of other scheduled work to focus on the problem, said Pat Ryan, a commentator on NASA TV.