Discovery Astronauts Wrap Up Tasks on Final Leg of Mission

After a 13-day mission in space, the seven astronauts aboard the shuttle Discovery buttoned up their craft Sunday and prepared for a landing here early this morning.

The landing was scheduled for 1:46 a.m. PDT.

Launches have historically been considered the most dangerous part of a shuttle mission, but the catastrophic destruction of Columbia during reentry in February 2003 had heightened anxieties about this landing.

For the first time, NASA took into account the possibility of damage on the ground if something goes wrong, changing the landing approach to avoid populated areas as much as possible.

In the past, shuttles headed for touchdown at the space center have flown directly over the southern United States. But debris from Columbia came close to striking Houston, forcing NASA to reevaluate its landing procedures.

Discovery was routed to bypass most of the United States, approaching Florida from the southwest after passing over Nicaragua and Cuba.

Commander Eileen Collins and pilot James Kelly spent their last few hours in space checking out flight control systems and practicing landings on a laptop computer, while the other astronauts made last-minute observations of Earth and made sure that all the cargo was properly stowed.

The crew was awakened at 5:39 p.m. PDT Sunday to the song “Come on Eileen” by Dexy’s Midnight Runners.

There was some time for relaxation.

Soichi Noguchi played with a baseball that had been signed by Japanese major leaguers, including New York Yankees outfielder Hideki Matsui. Seven players signed it, the Japanese astronaut said, to commemorate the seven lost crew members aboard Columbia.

Discovery’s astronauts accomplished all of their objectives for the mission, which was mainly to repair and replenish the International Space Station.

The mission, however, was marred by the discovery of several damaged areas on the shuttle.

The crew spent nine of their first 13 days in orbit transferring supplies to the space station, removing trash, installing a gyroscope and repairing a second one.

The space station has four large gyroscopes that enable it to keep its solar cells pointed at the sun. One gyroscope stopped working three years ago and a second failed in March, leaving the station with no room for error.

The station’s two-man crew waited until Discovery undocked before starting up the two gyroscopes. Mission Control told the astronauts Sunday morning that all four were working correctly.

“There’s lots of cheering on board Discovery right now,” Collins radioed back.

Discovery was loaded with nearly 7,000 pounds of garbage that had accumulated in the International Space Station since it was last visited by a shuttle in December 2002.

Russian spaceships have been able to resupply the space station with food, water and oxygen, but are not equipped to bring trash back to Earth.

The astronauts inspected their craft in space more thoroughly than any other shuttle crew had been able to and conducted the first repair of a shuttle in space.

In addition to many minor dings that were not thought to put the craft at risk during reentry, the inspection revealed two short strips of insulating fabric, called “gap fillers,” protruding between insulating tiles on the craft’s underside.

On Wednesday, astronaut Stephen Robinson rode below Discovery on the space station’s robotic arm and gently plucked out the two pieces of cloth, eliminating them as a potential hazard.

“It’s been an outstandingly successful mission,” said N. Wayne Hale Jr., deputy shuttle program manager. “We accomplished everything that we set out to do and more.”

Once Discovery is back on the ground, Hale said, NASA has a list of 47 potential problems -- “great and small” -- that must be addressed before the shuttle Atlantis could be launched on the next scheduled mission.

Foremost among them is the one-pound chunk of insulating foam that fell off Discovery’s external fuel tank during launch. It was about the same size as the piece of foam that put a hole in the leading edge of Columbia’s wing during its launch, leading to its ultimate destruction.

Discovery was not hit by the foam, but officials must determine why the piece broke off and find a way to prevent a recurrence before Atlantis can take wing.

If engineers find a quick solution, Atlantis could launch in September or November. If the damage represents a more fundamental problem, however, the launch could be delayed until next year or beyond.

The Discovery crew was confident that the problems would be resolved quickly.

“We’ll get back to flying very, very soon,” crew member Wendy Lawrence said.

Photographs taken in orbit also revealed part of an insulating blanket under the orbiter’s windshield had come loose during launch.

Engineers ultimately determined that it did not represent a hazard during reentry and that attempts by the astronauts to fix it might create more problems than they would cure.

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Maugh reported from Los Angeles and Johnson from Kennedy Space Center.