ISS spacewalkers to inspect joints Tuesday

Click the above photo to get an expanded image of the damaged solar array rotary joint.

Space station commander Peggy Whitson and flight engineer Dan Tani will make a spacewalk early Tuesday to inspect a damaged solar array rotary joint and a second beta gimbal joint, which recently appeared to be damaged.

"A priority is to take all the different panels off and look underneath," said Whitson during a press conference this morning. "If we have time we'll look under every single panel. We'll also take some samples (of metal shavings)."

Earlier inspections have found pits and metal debris on a 13-foot diameter race ring that turns the alpha array. Astronauts will also inspect a beta gimbal joint, which could have been struck by a micrometeorite. Each joint helps turn the solar wing on a different axis to face the sun so it can generate maximum electricity.

"We will bring in trundle bearing No. 5," said Whitson. "The ground has data that suggests that's where the problem is."

NASA managers don't want spacewalkers to transfer power to a backup SARJ ring before they understand why the first one failed.

"The big, key queston is what caused this," Kirk Shireman, International Space Station deputy program manager, said. "That's a very EVA intensive task and we do give up some redundancy."

This will be the 100th spacewalk for space station assembly.

"We're pleased to get through 99 of them without any major problems," said Tani, who had been scheduled to come home on STS-122 before Christmas. Atlantis' flight was delayed by a malfunctioning low-fuel sensor.

The spacewalk will be Tani's third and Whitson's second trip to the joint, which must be repaired so the solar arrays can produce full power to support additional laboratories.

Tani has been trained to repair the beta gimbal joint, and there is a spare part now on the space station.














Whitson, left, and Tani.