On Thursday officials of the National Aeronautics and Space Administration (NASA) said the computer problem posed complications but were optimistic the space shuttle Atlantis's mission would continue as planned.

"We've got a challenge. We'll figure out a way to get this behind us. We've got time," NASA associate administrator Bill Gerstenmaier said in Houston, Texas.

As engineers in Moscow and Houston tried to figure out what triggered the computer problem, Gerstenmaier said there was only "an extremely remote chance" that it could force the shuttle and ISS crews to abandon the station.

The glitch appeared in Russian computers that control the ISS's oxygen and water supplies and the stability of the orbiting station.

Meanwhile astronauts prepared for the third of four spacewalks -- this one to repair a patch of thermal blanket on the rear of the shuttle that was peeled back during liftoff last week.

During their outing scheduled to start at 1738 GMT Friday, two astronauts will try to pin the blanket back into place with surgical staples. The torn fabric could pose a hazard to the graphite structures underneath as the craft returns to Earth.

The computer problem -- the first such mishap of its kind -- arose overnight Wednesday with "computers going off-line," NASA spokesman Bill Jeffs told AFP.

Later on Thursday, engineers in Moscow "reestablished communications" with the module and Russian central computers, Jeffs said.

The problem was probably caused by a huge new solar power panel installed by US astronauts, a Russian space construction firm said Thursday.

"Russian specialists believe that the new solar panel installed by the Atlantis astronauts during their spacewalk could be the origin (of the breakdown)," said Irina Gomenyuk, a spokeswoman for Energia, which designed much of the station.

This "new powerful source of energy caused a malfunction of sensitive system elements" on the Russian and American segments of the station, in particular of the electrical supply system, Gomenyuk was quoted as saying by ITAR-TASS.

ISS director Mike Sufredini said some kind of electromagnetic interference could be causing the computers to switch off.

"The leading theory today is perhaps there is some noise, either environmental, radiative noise or a conductive noise, maybe in the power lines, that is causing the computers to shut themselves down," he told a news conference on Thursday.

The Russian computer systems control thrusters to orient the space station's position when US gyroscopes are not available. Thrusters on the Atlantis are now serving as a back-up to control the attitude of the station.

NASA could decide to delay the return of the Atlantis to buy more time for engineers to fix the problem. A worst case scenario would see an evacuation of the three-member ISS crew, though NASA officials considered that highly unlikely.

The US space agency has also played down concerns over the tear to the thermal blanket since it was noticed after last Friday's launch.

But such damage is a concern after the Columbia shuttle disintegrated as it returned to Earth in February 2003. The disaster was caused by breaks in the shuttle's 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.

earlier related report
The International Space Station was rocked by hours of computer communications trouble Thursday, the latest problem the first space shuttle mission of the year has faced after a thermal blanket tear. After hours of a glitch in Russian computers that control the International Space Station's critical oxygen and water supplies, communications with the systems have resumed, NASA spokesmen said.

"We are in a stable configuration," NASA associate administrator for space operations Bill Gerstenmaier told a news conference in Houston, Texas.

"We've got a challenge. We'll figure out a way to get this behind us. We've got time," he said, adding that there was "an extremely remote chance that this problem will lead to abandoning the space station."

NASA spokesman Bill Jeffs told AFP that the problem had arisen overnight with "computers going off-line," in the first such mishap of its kind, which raised concerns the mission might have to be cut short.

But now "they have reestablished communications" with the module and Russian central computers, Jeffs said.

"The Russians report that they think it is a power problem and not a software problem" that triggered the potentially problematic glitch, Jeffs said.

Indeed, the Russians believe the glitch with the Russian computers on board the ISS was probably caused by a solar panel installed by US astronauts, a Russian space construction firm said Thursday.

"Russian specialists believe that the new solar panel installed by the Atlantis astronauts during their spacewalk could be the origin (of the breakdown)," said Irina Gomenyuk, a spokeswoman for Energia, which designed much of the station.

This "new powerful source of energy caused a malfunction of sensitive system elements" on the Russian and American segments of the station, in particular of the electrical supply system, Gomenyuk was quoted as saying by ITAR-TASS.

ISS flight director Holly Ridings added that the Russians "were able to reestablish communications with the central computer on board the Russian segment of the ISS.

"They have been able to send commands to the system in the service module ... It looks they made a lot of progress overnight (and) we'll talk to them as we have been doing all night through the next couple of days to understand what caused the issue," she said.

Another NASA spokesman, John Ira Petty, said the problem had not been entirely fixed by 1255 GMT Thursday, but that the communications reconnect was "certainly a step in that direction" after many hours of interruption.

"There is some cleaning up left to do after a situation like this as you can imagine. But we are optimistic," he added.

Two US astronauts spent more than seven hours outside the International Space Station Wednesday working on its solar power panels as part of a huge expansion of the station's generation capacity.

Pat Forrester and Steve Swanson, who arrived at the ISS Sunday aboard the NASA space shuttle Atlantis, undertook the second of a total four spacewalks for construction and inspection purposes during the Atlantis's 13-day mission in space.

The two worked 90 minutes on a 73-meter (240-foot) older solar array on the starboard side of the ISS, "fluffing" it, NASA said, to ease full retraction on Thursday.

But they only succeeded in folding up 13 of the unit's 31.5 array bays before NASA took them off the job.

The next space walk is scheduled for Friday, during which astronauts will try to repair a damaged insulation blanket on the Atlantis which peeled back after liftoff at the rear of the shuttle, exposing a small underlying area that theoretically could be hazardous to the graphite structures underneath as the craft returns to Earth.

NASA aims to have the astronauts pin the blanket back into place with surgical staples.

The US space agency has played down concerns over the tear to the thermal blanket since it was noticed after last Friday's launch.

But such damage is a concern after the Columbia shuttle disintegrated as it returned to Earth in February 2003. This was due to breaks in its heat shield caused by 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 overcome the problem, modifying the external fuel tank and setting procedures to check the heat shield while in orbit.

earlier related report
Atlantis return may be delayed for third day by computer reboot
MOSCOW, June 14 (RIA Novosti) - The return of the U.S. Atlantis STS-117 space mission may be delayed for a third day because of lengthy computer reboot at the International Space Station, an expert with Russia's Mission Control told RIA Novosti Thursday.

"I think that the reboot [of ISS's six computers] will take no less than a day," the expert said.

Although this will be the third extra day for the STS-117 crew, the expert, who asked not to be named, said, "the Space Shuttle has enough power and oxygen in reserve."

"The main issue is to overcome problems with the computer before the Atlantis undocks," he said.

Igor Panarin, the spokesman for the Russian Space Agency, promised that "the problem will be corrected soon."

Meanwhile, the astronauts are planning their third spacewalk during this mission to finish their planned operations and repair thermal insulation on the shuttle prior to re-entry.

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Space Station News at Space-Travel.Com

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