NASA Eyes Potential Fix for ISS Computer Glitch

HOUSTON -- Astronauts aboard the International Space Station (ISS) will physically unplug a pair of cables feeding power from new solar arrays to the outpost?s Russian segment late Thursday in hopes that it might aid the recovery of critical computer systems, mission managers said.

?The leading theory today is, we?ve introduced some noise at a level that, now, these computers are tripping themselves off,? NASA ISS program manager Mike Suffredini said.

The German-built computers used in the station?s Russian segment are known to be susceptible radiant or conductive ?noise? in power feeds, which led ISS engineers to suspect that a similar phenomenon may be at work in cables ferrying power from the station?s new solar arrays at the tip of the Starboard 4 power truss installed earlier this week. ??

?It seems that shortly after we made those connections our Russian colleagues started having problems,? Suffredini said, adding that, if proven, it would hint at some anomaly in the new solar wings. ?The power source coming from the solar arrays that have been on orbit has been very clean, if you will. We?ve been well within our power quality specs.?

The theory is by no means final, but will be tested along with others to determine exactly what prompted a major shutdown of the station?s Russian computer systems Wednesday. The shutdown left the ISS dependent on U.S. attitude control systems and thrusters aboard the visiting Atlantis shuttle.

NASA officials expect the troubleshooting efforts to run several days, and hope to recovery the computer systems before Atlantis leaves the ISS on June 19.

?We do these things one step at a time,? Suffredini said. ?We try not to shotgun these fixes.?

To test the possible fix, astronauts will open up access panels in the station?s Unity node, then manually disconnect cables that feed S4 solar array power into converters that, in turn, route it into the Russian modules. The modules will rely on a previous power configuration to draw electricity generated by solar arrays at the portside end of the ISS, Suffredini said.

?This sounds like a good plan,? said Atlantis mission specialist Sunita Wiliams, who until recently served as an ISS crewmember, after Mission Control relayed it to the station crew today. ?We?re looking forward to trying to get these computers back online.?

Some of the station?s Expedition 15 crew will have to wake up overnight to aid Russian flight controllers in troubleshooting the computer glitch. The work has affected the crew?s sleep schedule since it can only be done when the ISS passes over Russian ground stations early in the day, NASA said.

Meanwhile, Atlantis shuttle astronauts spent much of today preparing for a Friday spacewalk and continuing efforts to furl an old solar array reaching out to starboard from the space station?s mast-like Port 6 (P6) truss.

Atlantis? STS-117 mission specialists Jim Reilly II and Danny Olivas will step outside the ISS Friday to repair a torn heat shield blanket on the orbiter?s aft, install a vent valve for a new ISS oxygen system and help coax a stubborn solar array into its storage boxes atop the space station?s mast-like Port 6 truss.

Efforts to retract the solar array, which was partly furled during a Wednesday spacewalk, met some additional success today as astronauts remotely guided a few more sections into storage boxes. About half of the array?s 115-foot (35-meter) length remains to be packed away during Friday?s spacewalk.

?That?s good news,? said NASA astronaut Megan McArthur, serving as spacecraft communicator in Mission Control. ?We?re halfway there.?

NASA is broadcasting the space shuttle Atlantis' STS-117 mission live on NASA TV. Click here for mission updates and SPACE.com's video feed.

• SPACE.com Video Interplayer: Space Station Power Up with STS-117
• STS-117 Power Play: Atlantis Shuttle Crew to Deliver ISS Solar Wings
• Complete Shuttle Mission Coverage