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Astronauts to take spacewalk

NASA considers extending mission




National Aeronautics and Space Administration (NASA)
Space Exploration

(CNN) -- Discovery astronauts Steve Robinson and Soichi Noguchi will suit up and step outside at 4:44 a.m. ET Saturday for the first of three spacewalks.

They plan to test tile repair techniques in the payload bay and repair a gyroscope on the international space station during the 6-1/2 hour spacewalk.

They will not be making any repairs to Discovery itself, said deputy shuttle manager Wayne Hale.

NASA managers are trying to determine whether repairs need to be made to any of the two dozen small dings the spacecraft's thermal tiles sustained during launch.

By comparison, inspections of past shuttle missions have turned up an average of 150 dings to the tiles during launch and re-entry, a NASA official pointed out.

NASA officials said they are considering extending Discovery's mission an extra day to help space station crew members, who may have to go without another shuttle visit for some time to come.

NASA is expected to decide by Saturday whether to extend the mission, and by Sunday whether Discovery can safely return to Earth.

The extra time would give shuttle and space station crews more time to transfer materials and carry out additional maintenance, Hale said Friday evening.

All signs indicate that the vehicle sustained no serious damage, and astronauts most likely won't be called on to repair it, he said.

Discovery docked with the international space station Thursday and is scheduled to stay there until August 5. An extra day in space would push Discovery's landing to August 8.

NASA announced Wednesday it had suspended future shuttle flights until engineers can find out what causes foam to sheer off the shuttle's external fuel tank during launch.

The agency has spent millions of dollars to fix the problem after the 2003 Columbia tragedy. And yet, at least four pieces of foam fell from Discovery's external fuel tank during liftoff this week. One piece appears to have hit the wing. (Full story)

Falling foam damaged a wing during Columbia's launch, causing the spacecraft to disintegrate in the searing heat of re-entry to Earth's atmosphere during its descent from space. Discovery Commander Eileen Collins admitted that the falling foam "wasn't what we had expected."

"I don't think we should fly again unless we do something to prevent this from happening again." She said that she didn't think the orbiter sustained any serious damage, however.

Discovery's flight is the first space shuttle mission since the 2003 Columbia disaster. NASA Administrator Michael Griffin said he does not believe the foam problem will cause a lengthy delay in Discovery's mission schedule, and he did not rule out another shuttle flight this year.

"All we ever said ... was that we are not going to fly again until we fix it, and I think that is the right thing to do," he said at a news conference.

Areas of interest

While a detailed examination of Discovery's exterior, thanks to high-resolution cameras and lasers, showed no serious damage, Hale said, three areas of interest are being evaluated further:

  • Near the door covering the orbiter's nose landing gear, a piece of tile is missing, about three-quarters of an inch long, three inches wide and less than four-tenths of an inch deep. The missing piece is not deep enough to have breached the tile's outermost thermal barrier, Hale said. "I'm feeling very confident that this is not going to be anything significant for us to worry about."
  • At two locations on the underbelly of the orbiter, ceramic "gap fillers" -- which are placed in between tiles -- have protruded outward. The main concern is that the protrusions can change the aerodynamics of the spacecraft during re-entry, increasing the amount of heat the tiles will have to endure, Hale said. NASA engineers are running tests to determine how much the protrusions -- which have happened during previous shuttle flights -- might increase the heat and what effect that might have on the vehicle, he said.
  • On Friday, the crew used Discovery's robotic arm to inspect these areas and the leading edges of the shuttle's wings.

    The crew also attached to the space station the Raffaello Multi-Purpose Logistics Module, with its cargo of food, tools and replacement parts.

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