Space walkers pass shuttle test

Astronauts successfully complete a repair simulation outside Discovery

July 09, 2006|By MICHAEL CABBAGE | MICHAEL CABBAGE,ORLANDO SENTINEL

HOUSTON -- Two space walkers bounced around on the end of a "skinny little pole" 210 miles above Earth yesterday in a daring test for future shuttle repairs.

Astronauts Piers Sellers and Mike Fossum spent seven and a half hours outside shuttle Discovery on the fourth day of the ship's visit to the International Space Station. Anchored to a boom held by Discovery's robot arm, the pair checked out whether the 100-foot-long appendage was stable enough to support maintenance work on the shuttle's heat shield.

Sellers, who performed three space walks during a 2002 shuttle flight to the station, was the first to stand at the end of the boom. As he was hoisted to a spot above the shuttle's cargo bay, he pointed out the smoothness of the ride.

"Very steady," Sellers said. "It's like being on a slow elevator."

Moments later, with the Earth as a stunning backdrop, Sellers performed three sets of movements, leaning back and forth to simulate motions that would be used during repair work. The movements resembled an orbital calisthenics session.

"It gets easier as you go along, doing all these tasks, you know, at the end of a skinny little pole," Sellers said. "A little practice makes perfect - or adequate."

When his turn came, Fossum mimicked the motions of someone making repairs to the orbiter's heat-resistant tiles and reported that the operation was "no problem."

Later, with both space walkers at the end, the boom showed more movement, but the swaying quickly stopped. The preliminary results led shuttle managers to conclude that the test was a success.

"That's given us very good confidence," said Tony Ceccacci, the mission's lead flight director. "Hopefully, we'll never have to use it, but we know we have the capability."

Despite yesterday's success, it is unlikely Sellers and Fossum will have to use the boom again this mission to pluck a card-like piece of ceramic fabric from between heat-resistant tiles on Discovery's belly. Engineers have been analyzing whether a gap filler protruding more than an inch from the rear of Discovery's heat shield could raise temperatures to unacceptable levels during the ship's fiery descent through Earth's atmosphere.

A spacewalker performed two similar repairs during Discovery's flight last year. NASA officials are expected to announce today that a fix will not be needed this time.

Shuttle managers also finished their evaluation of questionable spots on two thermal panels that line the leading edge of Discovery's right wing. Engineers concluded yesterday that the spots would not pose a hazard for the shuttle's flight home.

With Discovery's heat shield poised to receive a clean bill of health, evidence continues to mount that changes made to stop the shuttle's fuel tank from shedding dangerous pieces of foam insulation have been effective. Mission managers characterized Discovery's condition as the best in the program's history "by far."

"This is the best, cleanest orbiter I've seen," said Steve Poulos, manager of NASA's orbiter project office.

Michael Cabbage writes for the Orlando Sentinel.

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