Discovery touches down after 14-day mission

President Bush also weighed in with congratulations. "It was an important step for NASA as it regains the confidence of the American people and begins the transition to the new mission we’ve set out for NASA," he said. "So congratulations, Commander Collins. It’s quite an achievement."

The first post-Columbia mission accomplished its two goals: to resupply the space station, and to test the inspection and repair techniques that NASA developed in the wake of Columbia's catastrophic breakup in 2003.

Collins highlighted these achievements at the post-landing news conference at Edwards and spoke at length about the importance of human space exploration. The mission was both "an absolutely breathtaking challenge" and a "huge achievement," she said. Space exploration, she said, "is making life on Earth better for all of us."

The biggest accomplishment, she said, was just "getting the shuttle flying again."

"The Columbia crew believed in what they did, they believed in the space mission," and so do we, Collins said. "I ask you to keep supporting us. ... Space exploration is a fantastic part of the human experience."

The new inspection techniques did show two significant problems: the chunk of foam insulation that broke off from the external fuel tank after launch and two protruding bits of filler material that had to be plucked off Discovery's belly during a spacewalk by Robinson.

This unprecedented repair job in space may be laying the groundwork for long-duration missions such as those talked about to the moon and Mars, Robinson said Tuesday.  "Things are going to fail," he said, and this kind of up-close work with the shuttle skin showed what could be done when they do.

Robinson also paid tribute to Lawrence, who operated the robotic arm that maneuvered him so close to the shuttle's exterior. She "has no windows," he pointed out. "It's like flying a jet by watching TV." He said he felt very comfortable in position, like he could have done several different repairs there had he needed to.

Discovery's flyaway foam was detected thanks to unprecedented in-flight imagery of the shuttle's ascent, and the dangling gap fillers were noted during the most detailed on-orbit inspections ever conducted. The inspections turned up still more flaws, including minor damage to shuttle tiles and a torn thermal blanket — but NASA decided those posed no risk to Discovery's safe return.

Collins said she took a quick look at the thermal blanket after landing, and it did not look like there was a significant change on re-entry. She wasn't concerned about the blanket, she said, and praised NASA for making a good decision.

Such problems might have gone unnoticed on past flights, because the inspection procedures were not nearly as rigorous. NASA officials said the problems were all part of the challenge of operating an experimental space vehicle — which is how they have come to see the shuttles since the Columbia disaster.

Investigators said Columbia and its crew were lost because a piece of flying foam — bigger than the one that was seen coming off Discovery's tank — struck the orbiter's left wing, opening up a gap that let hot gases in during Columbia's atmospheric re-entry 16 days later. They also faulted NASA's "broken safety culture" for not paying close enough attention to things that might go wrong.

'We felt very safe'
As part of a $1.5 billion effort to remedy those faults, NASA added scores of cameras to record Discovery's launch, built a new kind of laser- and camera-equipped inspection boom to survey the shuttle's protective skin while on orbit — and encouraged more open discussion of potential problems. Discovery's astronauts tested patches and fillers that could be used to mend gaps in the shuttle's tiles or reinforced panels, and NASA said those repair tools would be improved for future flights.

Collins praised the shuttle and the people who built it. "The space shuttle orbiter performed magnificently," she said, every system "worked perfectly." There were a "few microswitch problems here and there," she said, but the "folks that built this orbiter and maintained it did a fantastic job and we felt very safe."

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