After shuttle repair, NASA weighs one more fix

SPACE CENTER, Houston - A spacewalking astronaut gently pulled two potentially dangerous strips of protruding filler from Discovery’s tile belly with his gloved hand Wednesday, successfully completing an unprecedented emergency repair.

Even as they celebrated spacewalker Stephen Robinson's feat, NASA managers weighed whether to attempt yet another repair job, this time involving a ripped and puffed-up thermal blanket just beneath commander Eileen Collins' cockpit window.

Mission managers could add another spacewalk to Discovery's schedule as early as Friday to have the loose section cut away — or they could decide that the blanket poses no hazard for Discovery's return to Earth. To resolve the issue, NASA flew samples of the blanket material from Kennedy Space Center in Florida to Ames Research Center in California for wind-tunnel tests overnight, deputy shuttle program manager Wayne Hale told reporters.

The blanket — a quilted fabric covering pillowlike stuffing — was most likely ripped open by launch debris and puffed up with air. Hale said engineers determined that if the ripped section came apart during re-entry, the biggest piece of debris would weigh less than an ounce. However, even tiny bits would pack "a lot of energy" if they were to hit the shuttle at supersonic speed, he said.

NASA A NASA image, looking down at the shuttle Discovery's cockpit from above, highlights the section of damaged blanket beneath the commander's window.

"Worst-case, we could do some structural damage, and that's obviously not something that we want to incur," Hale said. He said a final decision on whether or not to do a spacewalk would come on Thursday.

"That’s really the last thing on my to-do list for this flight," said Hale, who heads Discovery's mission management team.

Repeatedly during the course of Discovery's mission, NASA managers have had to countenance safety questions about matters ranging from the shedding of fuel-tank foam insulation to the ripped thermal blanket and the protruding gap fillers. Hale said the increased attention was a result of NASA's improved capability to spot flaws on the shuttle — which was part of the agency's plan to recover from the Columbia disaster in February 2003.

Hale said the heightened safety awareness would be a part of every shuttle flight from now on. "It's not a distraction — it's more like, that's what our job is," Hale told reporters.

Intricately choreographed repair
In the case of the gap fillers, NASA officials said there was a chance that the exposed ceramic-fiber fillers could lead to overheating on the shuttle's tiles or reinforced panels — and a possible repeat of Columbia’s disastrous re-entry. They said it was also possible that the protruding gap fillers posed no threat at all, but they decided not to take the risk. So NASA chose to go ahead with an intricately choreographed repair operation.

Discovery's crew flawlessly executed a plan that was drawn up in just four days: Robinson attached a special foot restraint to the space station’s 58-foot (18-meter) robotic arm, and fellow astronauts aboard the station maneuvered the arm so that Robinson could reach the shuttle’s belly. They were careful to make sure Robinson’s helmet and feet did not contact the fragile ship.

It was the first time an astronaut ventured beneath a shuttle.

Robinson took only the essential tools for the repair, leaving a tile repair kit just outside the airlock. He also secured his safety tethers between his legs and behind him to keep from accidentally striking the vehicle.

Once under Discovery’s belly, Robinson expected to spend about an hour removing or trimming the fillers from two locations near the shuttle’s nose — using a forceps and a makeshift handsaw if necessary. But it took mere seconds for him to pull each strip.

“That came out very easily, probably even less force,” Robinson said of the second piece. “I don’t see any more gap filler. ... I’m doing my own inspection here. It is a very nice orbital belly.”

His spacewalking partner, Soichi Noguchi, watched from 75 feet (23 meters) away, from a perch on the space station.

“Steve, we trained for four years; you’re going to spend the next four years signing autographs,” Noguchi told Robinson once the repairs were complete.

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