Spacewalkers give Alpha a surge

Slack in the cables

The weightless duo also trained one of their new helmet-mounted cameras on a nettlesome problem: some cables that should be pulling one set of the solar wings nice and taut. They have turned out to be slackers. The TV images from space were used by experts on the ground to conjure up plans for a fix.

NASA believes two of the cables jumped off their reels during the deployment of the 110-foot wing on Sunday. As the shimmering gold panels unfurled, some of them got stuck and bunched up. When they broke free, they caused a series of rapid, strong recoils that apparently knocked the cables out of their grooves.

While the arrays are generating power to specifications, NASA is concerned they are so vulnerable in their slackened state that a docking spacecraft might damage the fragile solar collecting cells.

Engineers also believe a docked shuttle would not be able to safely use its large thrusters to give the station an upward boost, for fear of damaging the limp wing. While no shuttle re-boosts are planned for this mission, they are an integral part of the long range plan to preserve station fuel while keeping Alpha in its desired orbit.

Repair to be attempted Thursday

While Tuesday's spacewalk was under way 230 miles above the planet, NASA astronauts John Grunsfeld and Mike Foale suited up and dove into the massive pool in Houston used to train spacewalkers -- the so-called Neutral Buoyancy Lab.

Although NASA does not have a solar array mockup with enough detail to practice the specific repair, the submerged pair did verify that their colleagues in low Earth orbit can reach the area where the trouble appears to be using some foot restraints attached to the station. Mission managers approved the scheme Wednesday, and the ad hoc repair will be added to the chore list during Tanner and Noriega's third and final spacewalk on Thursday.

"We think we have a really good plan in place -- it is a fairly simple task, we believe," said NASA spacewalking coordinator Glenda Laws. But she added they are readying a fallback plan to handle more complex scenarios -- should they crop up.

On Tuesday, Tanner and Noriega spent the latter half of their six hour and 35 minute weightless workday disconnecting 15 cables and fluid lines that link a docking port called Pressurized Mating Adapter 2 to the station. That piece sits in the spot destined for Destiny in January. PMA-3 will be moved temporarily to make room for the lab -- and then latched on to Destiny's outer end.

"You guys are doing a great job," said Endeavour astronaut Marc Garneau, who is serving as spacewalk choreographer.

"Flattery will get you everywhere," replied Noriega as he worked.

With the spacewalk complete, Endeavour's crew successfully deployed the second radiator on the solar array package and briefly entered the space station airlock to deposit more items to be picked up later by the Alpha crew. The hatches have remained closed between the two ships this week because the cabin atmosphere in Endeavour was lowered to protect the spacewalkers from developing the "bends." The station atmospheric pressure was not lowered.

Only after Thursday's spacewalk is complete will the shuttle cabin pressure be increased -- allowing Endeavour and Alpha Commanders Brent Jett and Bill Shepherd to open a series of hatches and shake hands at the threshold of their two spacecraft. The hatches will remain open for about 24 hours, allowing for the transfer of more provisions and equipment for the station crew.

Endeavour is scheduled to return home to the Kennedy Space Center in Florida on Monday.