Space station glitch puzzles the experts

James Oberg NBC News space analyst

HOUSTON - The failure of all six main control computers on the international space station's Russian segment has baffled space engineers in Houston and in Moscow. Temporary repairs aren’t enough. If the cause of the sudden simultaneous failures cannot be quickly identified and remedied, the space station's future operations are under threat.

The German-built computers, which operate in pairs, went out Wednesday morning, and several attempts to reboot them were unsuccessful. By Thursday morning, some basic communication functions were briefly restored, but the computers failed again after only seven minutes. An understanding of the root problem was still far off.

Controllers at Russian Mission Control told the station's two Russian crew members to take catnaps during the day, because they would be up all night once the station was back in direct radio contact with Russia and serious debugging could begin.

The glitch appears to be the space station's most serious computer failure since 2001, when the control computers on the U.S. side of the station experienced a cascade collapse that nearly lobotomized the station. Another computer failure, on the day the station's first component was launched in 1998, nearly caused the module to crash.

During Wednesday night's status report at Johnson Space Center here, NASA space station manager Michael Suffredini said engineers still had plenty of tricks to try, and he expected that they'd find a solution to the problem in the next few days. "I’m not thinking this is something we will not recover from," he told reporters.

Nevertheless, his space team is preparing to keep the shuttle Atlantis docked to the station for another full day, beyond the two already added for repairing a rift in the shuttle's thermal insulation blanket. That extra time would provide support to the Russian flight controllers in their troubleshooting activities.

To create a "power margin" for what could be a 14-day shuttle mission, shuttle astronauts have begun turning off non-critical electrical systems. NASA has developed a special set of "jumper cables" that would allow the shuttle to draw additional power from the space station — but the first shuttle flight to carry this gear would be the next one, scheduled in August.

What the computers do
Without the control computers, the Russian rocket thrusters — both on the station itself and on the unmanned Progress freighters that bring up supplies — cannot be activated to orient the station in space.

The main pointing control comes from a set of gyroscopic stabilizers on the U.S. segment that use electrical power to spin in directions that twist the station into desired turns. But this hardware — the "Control Moment Gyroscopes," or CMGs — need occasional assistance from rocket thrusters for more forceful turns and to "dump" excess angular momentum (which arises when the gyroscopes spin too fast).

As long as the computers are inoperable, other critical equipment in the Russian segment cannot function. The devices for producing oxygen, controlling humidity and scrubbing excess carbon dioxide were inoperable at first. However, during the brief time that the computers were operating Thursday morning, circuit breakers on the station were reconfigured to create a power pathway for some of that gear.

“The lights, fans and potty are still working, thank God,” Suffredini said. Meanwhile, redundant systems on the U.S. side of the station can provide critical life support functions for awhile, and now some of the Russian equipment is again available on manual control.

Communication gaps are adding to the challenges for the Russian engineers:  Due to the collapse of the Soviet-era space communications infrastructure, the station is out of touch with Russian radio facilities for almost half of every day. Voice communications and basic telemetry readings are relayed via NASA’s 24-hour communications network, but the critical data needed to diagnose the computer malfunctions requires direct contact.

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