Space station computer crash a mystery

Cape Canaveral (Fla), June 17: Crews aboard the space shuttle Atlantis and the International Space Station revived the third and final part of the station's prime computer network and scoured the complex for the cause of the crash.

The computers, which control the station's position in orbit, were restored after station commander Fyodor Yurchikin and flight engineer Oleg Kotov hot-wired the systems to bypass suspect power sources.

A test to determine whether the computers could communicate with each other was pending before the system could be declared healthy and a departure date set for Atlantis, said NASA's space station program manager Mike Suffredini yesterday.

The shuttle currently is scheduled to leave on Tuesday and land at the Kennedy Space Center in Florida two days later.

An extra day may be added to the mission if more time is needed to fix or test the computers on the station, a 16-nation project that has been continuously manned since November 2, 2000.

Problems with the computer system started on Monday as astronauts installed the newest piece of the station's exterior spine, a massive beam that holds a pair of solar wing panels and a rotary joint so the wings can track the sun for power.

The computers are German-built but have Russian software.

So far, the best explanation for the crash is a subtle change in the space environment now that the station's size has grown, Suffredini said.

As the station flies 355 km above Earth, it plows through streams of charged particles which create friction and build up a static voltage charge on the outside.

''As the station gets bigger, this potential continues to grow,'' Suffredini said. ''I think we're going to find system sensitivities as we change the space station.'' NASA, the US space agency, has 12 more major components to install on the 100 billion dollars complex before it is finished.

The work needs to be completed by 2010 when the US shuttles, the only vehicles capable of hauling the large pieces and assembling them in orbit, are retired.

The Atlantis crew already is staying an extra two days to get the station ready for the arrival of new laboratories built by Europe and Japan, which are scheduled for launch in 2008 and 2009.

A fourth spacewalk, scheduled for today, was added after managers decided to have astronauts fix a protruding insulating blanket on one of the shuttle's engine pods during the third spacewalk on Friday.

Engineers were concerned the blanket, which tore free during Atlantis' launch on June 8, could leave the shuttle's underlying structure vulnerable to heat damage during the plunge through the atmosphere prior to landing.

During the mission's final spacewalk, astronauts Patrick Forrester and Steven Swanson will finish work on the new solar wing's rotary joint and attempt to fix a hydrogen vent valve that is needed for a new oxygen generator.

Reuters

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