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NASA: No second repair needed

Astronauts salute those who sacrificed lives

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NASA engineers were concerned about thermal blanket damage on the orbiter.

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National Aeronautics and Space Administration (NASA)

JOHNSON SPACE CENTER, Texas (CNN) -- Discovery astronauts do not need to perform another repair to the shuttle's exterior, NASA engineers decided Thursday.

Mission control informed crew member Soichi Noguchi that a fourth spacewalk to fix a damaged thermal blanket under one of the cockpit windows was not necessary.

Tests and analysis of the blanket by NASA engineers concluded the orbiter was safe for return, mission control said.

"There is no issue," mission control radioed the crew.

Photos of the 20-inch-by-4-inch blanket weighing about 1 ounce showed it was punctured at one end -- possibly by debris -- and "poufed out" at the other.

Concerns were that the blanket would tear away during re-entry to Earth's atmosphere and strike the orbiter, especially when the shuttle slows from Mach 20 to less than Mach 6.

NASA engineers concluded that if a large piece of the blanket came off at supersonic speed at exactly the worst time possible the chances of it hitting the orbiter were 1.5 percent, deputy shuttle program manager Wayne Hale told a news conference Thursday.

Hale said engineers at the Ames Research Center in California, where fabric samples were sent for wind tunnel testing, concluded "they were not concerned about big pieces coming off."

"Our indications are that nothing will come off, or if at least it does come off it will be very small," Hale said.

"I'm not here to tell you that we are 100 percent confident that there is no risk during entry. ... We believe that the chances of anything happening with this piece of fabric is remote," he said.

Trying to repair the blanket in flight could do more harm than good, Hale said.

With the damaged thermal blanket issue settled "we have cleared Discovery to re-enter," Hale said.

Discovery is scheduled to return to Earth early Monday morning.

Fallen astronauts remembered

Thursday morning, Discovery and international space station crew members paid tribute to the fallen astronauts and cosmonauts who have given their lives for space exploration.

On February 1, 2003, the shuttle Columbia disintegrated over Texas on re-entry, killing all seven astronauts onboard.

The Columbia's STS-107 crew members were Rick Husband, Willie McCool, Michael Anderson, Dave Brown, Kalpana Chawla, Laurel Clark and Ilan Ramon.

Discovery's crew honored their friends and colleagues by wearing red shirts with the STS-107 patch. Each crew member provided words of tribute and remembrance.

"They believed in space exploration. They knew the risks, but they believed in what they were doing. They showed us that the fire of the human spirit is insatiable," mission specialist Charlie Camarda said.

"To the crew of Columbia, as well as the crews of Challenger, Apollo 1 and Soyuz 1 and 11, and to those who have courageously given so much, we now offer our enduring thanks," said space station crew member John Phillips.

"From you we will carry the human spirit out into space, and we will continue the explorations you have begun,"

'A ride of a century'

On Wednesday, shuttle astronaut Steve Robinson removed fabric gap fillers from Discovery's exterior during his six-hour spacewalk.

The fillers were sticking out from heat-resistant tiles on the shuttle's belly.

NASA had worried that protrusions of the fabric would cause excessive heating during re-entry.

"I'm grasping and pulling. ... It's coming out very easily. ... Beautiful," Robinson said during the procedure.

The challenge he faced was to remove the gap fillers without damaging the tiles, which protect Discovery from the 2,300-degree heat of re-entry. If that happened, the repair could pose more of a threat than the original problem.

Robinson called the spacewalk "a ride of a century," as Discovery's robotic arm maneuvered him to two areas along the spacecraft's underside near the nose.

His wireless mounted camera provided a spectacular view of the shuttle's hull as the craft orbited more than 220 miles above Earth.

"My eyes have never seen such a sight," Robinson said. (Full story)

"Stand tall and lean forward," NASA's mission control said as it moved him closer for the repair.

He carried forceps and a makeshift hack saw -- fashioned on the fly Tuesday by Discovery's crew -- in case he could not remove the fillers by hand.

The fillers are made from thin fabric stiffened with a ceramic material and plug gaps between the tiles.

Damage to the tiles was blamed for the loss of the shuttle Columbia, which broke up up during re-entry over Texas in February 2003, killing all seven astronauts on board.

Discovery's mission, which began July 26, is NASA's first manned flight since that disaster.

"We proved we can get access to the bottom of the vehicle," said Cindy Begley, the Houston-based flight controller in charge of the spacewalk. "We just never needed to do that before."

She said the most important accomplishment of the flight has been the use of the robotic arm to view the entire underside of the shuttle.

That inspection -- mandated after the Columbia disaster -- turned up the protruding gap fillers.

Discovery flight director Paul Hill said he was "absolutely relieved" by the ease of the repair.

"You could hear sigh of relief through the building over there," he told reporters. "When he pulled the second one out, it was a huge relief. It's all downhill from here."

The spacewalk began at 4:48 a.m. ET, about a half-hour later than scheduled, and ended at 10:49 a.m.

Robinson and Noguchi first had to install a new storage platform to the exterior of the international space station, with which Discovery has been docked since last week.

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