Computers on Space Station Crash; NASA Weighs Options if Repair Fails
Friday, June 15, 2007
Russian and NASA engineers worked into the evening yesterday to figure out why two computer systems essential to the operation of the international space station crashed, and the agency began making contingency plans that include potentially abandoning the $100 billion facility if they should fail.
NASA officials said that the situation appeared to be improving and that some communication had been restored to the Russian computer system. But NASA's space operations chief, William H. Gerstenmaier, said yesterday that the failure is complicated and will probably take days to fix.
"At this point, we don't know the root cause of the problem," he said. "Fortunately, we have a lot of flexibility in terms of timing."
The computer systems -- which began to have problems the day after new solar panels were deployed, creating an additional source of electric power -- control thrusters that keep the station properly oriented. They are also used to control the oxygen-production and carbon-dioxide scrubbing systems for the air that the astronauts breathe.
The three-person crew of the station was joined this week by a seven-member team on the space shuttle Atlantis. NASA officials said they are currently in no danger.
Michael T. Suffredini, manager of the space station program at the Johnson Space Center in Houston, said that intensive work to restore the computer functions began yesterday morning, when the station's orbit brought it near its Russian control station, and would continue through the day.
He said the computers -- which were made in Germany by Daimler-Benz and were donated by the European Space Agency -- may be especially sensitive to "noise," or variations in an electric signal that can cause static. That noise, he said, may have started after the new array of solar panels was connected.
Suffredini said that he fully expects the computer problem to be resolved. "I'm not thinking this is something we will not recover from," he said.
As a precaution, he said, NASA is looking into options to further extend the shuttle's stay, since its power and thrusters could be used to keep the station properly situated to keep the solar panels facing the sun. Mission Control had decided to extend the 11-day mission by two days to allow ample time to repair a damaged portion of the shuttle's thermal insulation. Returning the station's crew to Earth -- most likely aboard the emergency Soyuz spacecraft docked at the station -- would be the worst-case scenario.
The Russian computers appeared to be stuck in a rebooting cycle, and their failure led to a number of false fire alarms. While the astronauts continued their troubleshooting, NASA officials said, nonessential power use was being restricted.
Gerstenmaier acknowledged that the computer problem is serious, but said that crew members and ground control were working on solutions.
"I think we're stable," he said. "In my world, this is space station operations."
Gerstenmaier said that the computer failure had turned off the machine that removes harmful carbon dioxide from the air inside the space station, but that backup systems were taking over the task.
On Monday, two of Atlantis's astronauts attached a new 36,000-pound solar array truss segment to the station, giving the orbiting space facility an additional 20 kilowatts of power. One Russian command-and-control computer failed on Tuesday, and the other two failed on Wednesday night.
The computers on the Russian segment of the space station, called Zarya, control the lab's orientation and can adjust the space station's orbit by firing rocket thrusters in the Zvezda command module. If the Russian oxygen-production machine cannot be restored, the space station has available a 56-day supply of oxygen.
The Atlantis astronauts have conducted two spacewalks this week and have a third scheduled for today to repair the piece of protruding insulation near the rear of the shuttle. A corner of the thermal blanket pulled away from the housing of the orbital maneuvering system engines during launch.
NASA engineers said that they do not think the damaged section of the thermal blanket will endanger the spacecraft as it passes through the intense heat of reentering Earth's atmosphere, but that it could cause damage requiring time-consuming repairs to the shuttle. Because of the fatal 2003 Columbia disaster -- caused by damage to a critical portion of heat shielding on the shuttle's wing -- NASA is especially sensitive to any problems that could affect the shuttle's reentry.