"They got them running around 3:00 pm (1900 GMT)," NASA spokeswoman Brandy Dean told AFP, adding that the technical teams were monitoring the system to see how it reacted to the adjustments.

"For now it's working," she said. "This is good news. It's very encouraging."

Astronauts used a jumper cable to bypass a faulty power switch, NASA said on its website. The computers will run overnight for testing in the morning.

Russian flight controllers blamed the glitch on installation of the ISS' new solar panels, but head of the Russian space operator RKK Energia said he did not blame the visiting crew for the problem.

"This is just a coincidence," Nikolai Sevastyanov said.

Mike Suffredini, space station program manager, said: "I think we're in good shape. We still have a lot of options to go through to recover these machines. We've got a talented group of people to look at attitude control."

Although the computers stabilize the station in orbit and manage critical oxygen and water supplies, the crew was not in danger, Suffredini said.

"We are in a very good position from a life-support perspective," Suffredini said. "We have plenty of oxygen on board," he said from the Johnson Space Center in Houston, Texas.

With the computers off line, the station's gyroscopes kept the orbiting laboratory on an even keel, with the propulsion system of the docked shuttle Atlantis providing backup, NASA said.

NASA associate administrator Bill Gerstenmaier said there was only "an extremely remote chance" that the problems could force the shuttle and ISS crews to abandon the station.

Russian mission official Sergei Krikalyov told CNN earlier Friday that the glitch "may create some problems but for sure no kind of crisis" thanks to backup systems.

Russia may send its cargo vessel Progress to the ISS earlier, on July 23 instead of its planned August launch, to deliver spare parts for the computers, an official said.

Meanwhile, astronauts completed the third of four planned spacewalks -- this one to repair a patch of thermal blanket to the rear of the shuttle.

The space walk lasted two minutes short of eight hours, ending at 0122 GMT, Saturday, and astronauts used surgical staples to pin down a corner of the blanket, which came loose as the shuttle reached escape velocity from the Kennedy Space Center on June 8.

NASA engineers stressed that the hand-size opening posed no threat to the crew, unlike the broken tile that caused the Columbia to break up on re-entry in February 2003.

That disaster was caused by breaks in the shuttle's ceramic heat shield due to foam insulation peeling off its fuel tank and striking a wing during the launch.

All seven astronauts aboard perished and the shuttle program was put on hold for nearly two and a half years while the space agency sought to solve the problem, modifying the external fuel tank and setting procedures to check the heat shield while in orbit.

The loose blanket on the Atlantis covers a part of the engine on the top side of the craft, which is not exposed to nearly as much heat as the wing of the Columbia.

NASA has decided to prolong the mission two extra days until June 21 to make time for the repair.

Time permitting, the space walkers will also try to complete the job of folding up a bulky set of solar panels so that they can be returned to their box for later re-installation elsewhere on the space station.

NASA report
Navigation Computers Troubleshooting Efforts Continue
Friday afternoon, the crew inside the International Space Station was able to power-up two lanes of the Russian Central Computer and two lanes of the Terminal Computer by using a jumper cable to bypass a faulty secondary power switch. The current plan is to allow the computers to operate overnight and analyze the data Saturday morning.

Earlier in the day, International Space Station Program Manager Mike Suffredini told reporters Russian and U.S. flight controllers and engineers are focusing on efforts for recovering the computers and options to maintain attitude control until the problem is resolved.

"I think we're in good shape," Suffredini said. "We still have a lot of options to go through to recover these machines. We've got a talented group of people to look at attitude control."

The navigation computers provide backup attitude control and orbital altitude adjustments. For now, the station's control moment gyroscopes are handling attitude control, with the shuttle's propulsion system providing backup.

NASA report
Crews Work Together on Station, Shuttle
The Expedition 15 and STS-117 crews continue to conduct joint operations aboard the International Space Station and Space Shuttle Atlantis.

Throughout the week, the two crews have been activating the Starboard 3 and 4 (S3/S4) truss segment that was attached to the station on Monday.

The STS-117 crew has conducted three spacewalks to prepare the new segment for activation and to retract arrays on the Port 6 (P6) truss. The P6 will be relocated from atop the station to the end of the Port 5 truss by a future shuttle crew.

The S3/S4, which is 45 feet long and weighs 35,678 pounds, contains a new set of solar arrays that will increase the station's power-generation capabilities. The S3/S4 also contains a rotary joint that will allow its arrays to track the sun.

In addition to a new truss segment, NASA Astronaut Clayton Anderson joined the Expedition 15 crew on Sunday, replacing Flight Engineer Suni Williams. Anderson arrived at the station as a member of Space Shuttle Atlantis' crew. Atlantis docked to the station on Sunday. Williams spent six months as an Expedition crew member.

STS-117 arrived at the station June 10 and is scheduled to undock June 19.