The two balky Russian computers on the orbiting International Space Station have apparently been fixed by two Russian cosmonauts using a pair of old-fashioned "jumper cables" to bypass a malfunctioning switch.
In a news conference late Friday, Michael Suffredini, NASA's space station program manager, said that Russian Space Agency technicians came up with a repair procedure earlier Friday in their labs on Earth and sent details to the two cosmonauts.
"They implemented a simple shunt" by removing electrical connections to the computers and bypassing existing circuitry, Suffredini said. After powering up the two computers, which control water, oxygen and the orbital position of the space station, four of the six data channels or "lanes" again came online and began operating as designed, he said. The computers should work fine with four lanes in operation, NASA said.
"It did exactly what they expected," Suffredini said. Once the computer were confirmed to be back online, the Russian crew taped the shunt into place and reattached protective access panels. The four lanes on the two computers have been back in service since about 3:30 p.m. EDT.
The problem was apparently a low-voltage circuit similar to something seen in an overvoltage protection circuit, he said. Such a circuit can be affected by electromagnetic interference or "noise," which apparently caused it to turn the power off to the two Russian computers.
Bypassing the faulty mechanism restored the flow of electricity. "They basically caused the system to ignore this little switch," Suffredini said.
The Russians, who reactivated some of the cooling systems on the station that had been disabled by the computer problems, are letting the computers run overnight to make sure they are stable, he said. If the computers are still operating normally on Saturday, then other space station systems, including attitude positioning controls, will be brought back into operation.
"When we saw all that [working again] it was an indication that things have changed and changed for the better" aboard the space station, Suffredini said. "They do appear to be running and [performing] their functions."
The two Russian computers, which control water and oxygen as well as spacecraft orientation failed Wednesday, but the crew has not been in any danger because there are backup computers and other systems onboard, according to NASA.
NASA and Russian Space Agency personnel will continue to look into the problem and conduct detailed reviews to be sure that other space station systems don't include similar switches that could hamper future missions, he said. "I think our Russian colleagues took a major step at desensitizing these computers" to the hostile environment in space, he said. "We have not seen anything like this in the past."
The problem was urgent enough that the Russian space agency had considered the prospect of sending replacement parts into space next month -- two weeks earlier than a supply rocket was scheduled to depart -- if repairs couldn't be made, NASA said.