NASA scrambles to plan spacewalk to fix ripped solar wing
The agency wanted spacewalking astronauts to tackle the job Friday but had to push back the outing to Saturday to give officials on the ground more time to fine-tune the repair plan.
The solar panel tear is the more pressing of two major issues hampering power production on the orbital outpost. A rotary joint that controls the solar wings on the opposite side of the station is also causing problems.
Both issues threaten to disrupt future construction work at the station, including the planned December launch of a European lab.
But ignoring the wing damage could have even more troublesome consequences. If the damage worsened and the panel lost all power-collecting capability and became unstable, the wing would have to be junked, said Mike Suffredini, NASA’s space station program manager.
The wing ripped in two places as it was being unfurled Tuesday by astronauts aboard the linked shuttle-station complex, and a hinge may have been yanked and partially ripped.
Engineers suspect the wing became snagged on a support for one of the wing’s guide wires, Suffredini said. They do not want to reel it in to make it easier to access for spacewalkers, for fear it could be further damaged.
The torn section of the wing cannot be reached with the space station’s 58-foot robot arm. So NASA plans to attach the shuttle inspection boom to the robot arm and put astronaut Scott Parazynski on the boom to free the snagged part of the wing.
It helps that Parazynski is tall – 6-foot-2 – and has long arms. NASA doesn’t want him bumping the wing or touching its sunlight-collecting blankets. There would be no need to mend the tears.
Parazynski’s spacewalking plans have changed several times since the power problems cropped up last weekend.
He originally was scheduled to spend the fourth spacewalk testing a technique for repairing the shuttle’s thermal tiles. That task was added to the mission after a piece of fuel-tank foam gouged Endeavour’s belly on the last shuttle flight in August.
After a spacewalker found steel shavings in the right rotary joint last weekend, NASA ditched the test and asked Parazynski and spacewalker Douglas Wheelock to thoroughly inspect the joint.
Now, however, they planned to spend Thursday and Friday gathering the tools they will need for the wing repair and studying the techniques being developed on the ground for Saturday’s spacewalk.
At least one of the problems will need to be resolved before shuttle Atlantis can lift off with Europe’s lab, which is currently scheduled for Dec. 6.
Suffredini said he and others will figure out what to do about the joint once Discovery undocks from the space station. The shuttle is scheduled to undock on Monday and land on Wednesday.
Astronauts awoke Thursday to the repetitive "o-wim-o-weh, o-wim-o-weh“ of "The Lion Sleeps Tonight,“ a song sent up by their training team.
"That was a lot of fun,“ Discovery commander Pamela Melroy said. "That certainly gets you going first thing in the morning.“
Also Thursday, the astronauts planned to take a break to speak with former President George H.W. Bush while he visited Mission Control.
Last updated: 9:56 am Thursday, December 13, 2012