NASA: Spacewalk will have 'higher risk than usual'

— -- Astronaut Scott Parazynski, one of NASA's most experienced spacewalkers, will face grave risks and nerve-wracking challenges Saturday when he is scheduled to fix a damaged solar panel on the International Space Station.

Among the dangers Parazynski could encounter: potential electrical shock, sharp objects that could puncture his spacesuit and a long journey back to the safety of the station.

Then there's the risk of failure. If Parazynski can't fix the panel, the rip could grow, rendering the panel useless. Without the power the panel is supposed to generate, NASA would have to halt further construction on the station, including the addition of laboratories scheduled for December and April.

Parazynski's walk carries "a little bit higher risk than usual," says astronaut David Wolf, chief of NASA's spacewalking branch, but "there comes a time when the station needs repair … where we, with good mitigation and knowledge, accept a higher risk."

As astronauts inside the station issued commands to unfold the panel Sunday, a guide wire snagged. Before the unfurling could be stopped, the panel had two rips, a broken hinge and snarled wires.

NASA engineers, who did not think this could happen, have been working around the clock to stitch together a repair method. The plan calls for Parazynski to ride a jury-rigged work crane out to the damaged section, which is out of sight of his crewmates inside the station.

There he'll try to smooth the wires, either by untangling them or by cutting them. He'll thread metal strips that NASA has nicknamed "the cuff links" through holes in the panel to splint the tears and restore the panel's strength.

Among the difficulties Parazynski, 46, will face:

•Normally, an astronaut on a spacewalk is never more than 30 minutes' travel time away from the door into the space station, in case the spacesuit malfunctions. From his work site on the panel, Parazynski will need to ride the station's robotic arm for as long as an hour to get close to the door.

•The former emergency-room doctor will be doing delicate tasks while wearing stiff spacesuit gloves. Working in them is like "sewing with mittens on," Wolf said.

•The panel's solar cells, which can't be turned off, could give Parazynski a shock. He "really needs to be extremely careful to stay away from the solar cells," says Dina Contella, the lead spacewalk planner. "Just a kind of small slip and you could be touching it."

All Parazynski's metal tools will be wrapped in insulating tape, as will the metal parts of his spacesuit.

Parazynski seems ideally suited for the job. He has made six spacewalks. His height of 6 feet, 2 inches has earned him the nicknames "Too Tall" and "Longbow," which also means he has long arms. This allows him to reach the panel while staying relatively far away.

"We're darn fortunate to have him on this flight to go do this effort for us," station program director Mike Suffredini said Wednesday.

NASA originally had hoped to fix the panel Friday, but developing the procedures and tools proved too time-consuming. If the panel still needs repair at the end of Saturday's effort, it's possible officials would schedule another spacewalk to fix it, flight director Derek Hassmann said Thursday.