Advertisement

SKIP ADVERTISEMENT

2 Tugs, and the Protruding Strips That Vexed NASA Are Gone

WASHINGTON, Aug. 3 - Stephen K. Robinson, an astronaut with a Stanford Ph.D. in mechanical engineering, walked into space on Wednesday morning and repaired a worrisome problem on the shuttle Discovery with the simplest of tools: the thumb and forefinger of his right hand.

Perched on the end of the International Space Station's 58-foot robotic arm, Dr. Robinson, 49, easily removed two strips of cloth filler that had protruded above the surface of the heat-resistant tiles on the shuttle's underbelly.

"I'm pulling. It's coming out very easily," he said as he removed the first piece at 8:45 a.m. Eastern time. "Very nice."

About 10 minutes later, after being maneuvered to another position under the belly of the shuttle, Dr. Robinson reached for the second piece of filler, ceramic-covered cloth used to fill gaps between the shuttle tiles. With a clear view from a camera in his helmet, he slipped the cloth rectangle from between two tiles with hardly an effort.

"That came out very easily," he said from a vantage point 220 miles above the coast of France. "It looks like this big patient is cured."

Mission controllers had allowed up to an hour and a half for the operation, but it went so smoothly it took only a few minutes. Wednesday's spacewalk, which had been expected to last more than seven hours, ended after six hours and one minute.

Any misstep could have damaged the fragile tiles that cover the orbiter. The gap fillers, about six inches long and two inches wide, came out so readily that Dr. Robinson did not have to use any of the tools he carried, including a forceps, a hacksaw and a pair of scissors.

The gap fillers had come loose from their adhesive bond, probably during liftoff, and extended about an inch above the tiles. Engineers were concerned that the protrusions could change the aerodynamics of the superheated air that flows around the shuttle during its re-entry into the atmosphere early Monday morning.

Although there is evidence that shuttles have landed safely in the past with gap fillers extending from tiles, The National Aeronautics and Space Administration has been extracautious about safety since the Columbia and its crew were lost on Feb. 1, 2003, when the shuttle disintegrated upon re-entry because of damage to its left wing on liftoff.

N. Wayne Hale, the deputy manager of the shuttle program, said at a news conference late Wednesday that the Discovery had generally been cleared to make a safe landing. But Mr. Hale said engineers were still studying the potential risks of a damaged thermal-insulation blanket near the window on the commander's side of the shuttle.

The blanket is loose and torn, apparently because it was hit by debris during ascent, and the shuttle team is concerned that pieces of it could fly off during re-entry and strike the shuttle, causing some structural damage, he said.

Samples of the blanket have been flown to the Ames Research Center in California to be put into a wind tunnel to determine how the fabric might come apart and where the fragments might go, Mr. Hale said.

While unlikely, he said, it is possible that a fourth spacewalk to fix the blanket may be called for, and experts are developing preliminary plans for one.

Wednesday's spacewalk, the third of the mission, began at 4:48 a.m. Eastern time, with two astronauts, Dr. Robinson, the flight engineer, and Soichi Noguchi of the Japanese Aerospace Exploration Agency. They first moved to the station's Quest airlock and spent almost two hours installing a large external toolbox for which they had attached a mounting brace on their first spacewalk.

After repositioning the robot arm that had held hold the toolbox, the astronauts attached a special foot restraint for Dr. Robinson to stand in while riding the arm to the shuttle's belly to retrieve the gap fillers. After helping Dr. Robinson with his equipment for working under the orbiter, Mr. Noguchi moved higher up on the station to observe the operation and to help guide his partner.

The Discovery's pilot, Col. James M. Kelly of the Air Force, guided the station arm with Dr. Robinson on the end through a series of intricate maneuvers to the shuttle's underside, careful to avoid contact with any of the craft's 24,300 glass-coated tiles.

From his position in the space station, Colonel Kelly could not see the astronaut on the arm. Dr. Robinson called out the direction and distance he wanted to move, repeating the phrase "good motion."

Mission planners had not expected to see Dr. Robinson at work, because the area under the shuttle is often out of the cameras' line of sight. But as he neared the second gap filler, Dr. Robinson's helmet camera showed a clear view of the cloth poking out.

"Steve, could you move your hand out of the field of view?" another astronaut, Andrew S.W. Thomas, asked by radio. "We were enjoying the view as much as you were."

After Dr. Robinson finished removing the gap fillers and placed them in a bag he carried, he asked to be positioned farther back from the orbiter. His hobbies include painting and other visual arts (he also plays lead guitar in an astronaut band, Max Q), and he wanted to take pictures from his unique viewpoint.

He described the contrast of the curves of the shuttle against the sharp angles of the space station, saying, "Oh, my goodness, it's just beautiful."

"The surface of this belly," he said, "is a work of art."

A version of this article appears in print on  , Section A, Page 16 of the National edition with the headline: 2 Gentle Tugs, and the Protruding Strips That Vexed NASA Are Gone. Order Reprints | Today’s Paper | Subscribe

Advertisement

SKIP ADVERTISEMENT