EDWARDS AIR FORCE BASE, Calif. (AP) – On Earth and in space, it weighed heavily on everyone’s minds.

Discovery co-pilot James Kelly thought about it, experiencing what he called a “moment of trepidation.” Commander Eileen Collins thought about it too, no doubt reminded by the picture of the smiling astronauts on the flight deck. So did Dr. Jon Clark in Florida, thinking about his wife’s final moments on that tragic day 21/2 years ago.

The landing of Discovery brought back a flood of painful memories of Columbia on Tuesday as the shuttle glided to a smooth touchdown before sunrise, completing the country’s first manned space mission since the 2003 disaster.

At a news conference after landing, Kelly recalled that nervous moment right before Collins pushed the button for the shuttle’s fiery descent home. “I did think about the Columbia mission coming home, but I wouldn’t say it was a distraction but I would say it was more of a “We’re going to get through this and we’re going to press on,”‘ Collins said.

Columbia broke up over Texas on re-entry when a piece of fuel-tank foam insulation tore a hole in the left wing, killing all seven astronauts on board.

NASA had hoped that the problem would be fixed by the time Discovery lifted off July 26, but the takeoff was marred when a piece of the foam insulation flew off the fuel tank. This time, the foam did not damage the shuttle.

Despite the shaky start, Discovery made it home during an uneventful landing at Edwards Air Force Base after four landing attempts at its Florida home base were scratched due to rain and lightning.

“Congratulations on a truly spectacular test flight,” Mission Control said after Discovery came to a stop on the concrete runway at 5:11 a.m. PDT. “Welcome home, friends.”

Shuttle managers freely acknowledged the foam blunder, and NASA grounded all future shuttle flights until it can solve the foam problem.

But managers also stressed that the inspection, photography and other shuttle data-gathering systems put in place for this flight worked well. What’s more, they said no severe damage was detected on Discovery while it was in orbit.

“I hope this shows people that we’re coming back,” NASA spaceflight chief Bill Readdy said from Cape Canaveral, Fla. “We’ve got some more work to do. We know what we need to do and we’ll do it.”

“We’re going to try as hard as we can to get back in space this year,” NASA Administrator Michael Griffin said at a post-landing news conference. “But we’re not going to go until we’re ready to go.”

Unlike previous Edwards landings, in which throngs of spectators gathered in the Mojave Desert for a shuttle to return, the public was barred from viewing Discovery due to increased security after the Sept. 11 terrorist attacks.

The 17,000-mph plunge from orbit took Discovery through a passage of the same kind of intense heating that exposed the mortal wound in Columbia’s wing. The shuttle soared across the Pacific and over Southern California, passing just north of Los Angeles on its way to Edwards as it completed a journey that spanned 5.8 million miles and 219 orbits of Earth.

NASA adjusted the flight path in order to skirt Los Angeles because of new safety considerations imposed after the Columbia disaster, which rained debris onto Texas and Louisiana.

During Discovery’s approach, Clark, a NASA neurologist and husband of Columbia astronaut Laurel Clark, said he quietly remembered his wife and closely compared the two missions.

“I thought, ‘This is when the tire light went on,”‘ Clark said from Kennedy Space Center, referring to an initial sensor reading that Columbia was breaking up. “I was paralleling the two missions.”

Two hours after touchdown, the astronauts walked around the shuttle to inspect for possible damage. “It looks fantastic,” Collins said.

Collins said the United States should continue launching shuttles until the scheduled completion of the international space station in 2010.

“Some people say we should stop flying the shuttle because we had an accident – frankly we’ve had two accidents – but we are people who believe in this mission and we are going to continue it,” Collins said, referring to the Challenger and Columbia accidents.

NASA said it will be a week before Discovery leaves California, riding piggyback atop a modified Boeing 747 back to Cape Canaveral. The cross-country trip is expected to cost the space agency about $1 million.

Of the 111 shuttles that have landed since 1981, 49 came in at Edwards. The last shuttle to land at Edwards was Endeavor in 2002.

The switch to landing in California was a big disappointment for the astronauts’ families, who had been waiting two weeks to greet their loved ones in Florida. Astronauts planned to reunite with their families on Wednesday, when they are to meet in Houston.

Discovery’s crew accomplished its main objectives to resupply the international space station and fix broken equipment. The first shuttle to visit the space station since 2002, Discovery spent nine days docked to the orbiting lab.

Astronauts performed two planned spacewalks to test new repair techniques and replace a failed 660-pound, washing machine-sized gyroscope which helped control the station’s orientation. It is the first time in three years that all station’s gyroscopes were working simultaneously.

In a third unprecedented spacewalk, astronaut Stephen Robinson went beneath Discovery’s belly to pull out two protruding thermal tile fillers that engineers on the ground feared could cause overheating during re-entry and lead to another Columbia-type disaster. NASA canceled a fourth spacewalk to repair a torn thermal blanket near the cockpit window, saying that it posed little danger to the shuttle.

Associated Press Writer John Antczak contributed to this report.

On the Net:

NASA: http://www.nasa.gov/returntoflight/main/index.html

AP-ES-08-09-05 1944EDT

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