CAPECANAVERAL, Fla. - With the space shuttle Discovery back on Earth and its astronautcrew safe and sound, NASA is commending the successful spaceflight--the spaceagency's first since the Columbia accident--while admitting that more workremains to be done.
"Obviously,we're real pleased," NASA chief Michael Griffin told reporters in apost-landing briefing. "This is the first step back [into] our return to flightsequence."
Discoveryand its STS-114 crew, commanded by veteran astronaut Eileen Collins, landedTuesday at 8:11:22 a.m. EDT (1211:22 GMT), rolling to a stop on a concreterunway at Edwards Air Force Base in California. At 10:14 a.m. EDT (1414 GMT),Collins and her crewmates cracked Discovery's outer hatch and stepped back ontoterra firma.
"We havehad a fantastic mission," Collins said from the tarmac of Edwards' Runway 22after Discovery's landing. "We are so glad to come back and be able to say it'sa success."
But Griffin said that shuttle engineers and managers will take their time analyzing the data fromDiscovery's STS-114 mission, such as launch images and video depicting large piecesof insulation foam popping of the orbiter's external tank.
"We don'tlike that," Griffin said. "That's the only thing that went wrong with thismission in any significant way."
The foamdebris--which brought back memories of the lost Columbia mission--clouded aspaceflight in which the STS-114 astronauts performed flawlessly, Griffin added.
Launchedon July 26, Discovery's STS-114 mission was NASA's first shuttle flight sincethe 2003 Columbiadisaster, which destroyed one orbiter and killed seven astronauts. Columbiabroke apart while reentering the Earth's atmosphere on Feb. 1, 2003. ItsSTS-107 astronaut crew did not survive.
Investigatorslater traced the accident's cause to a 1.67-pound piece of external tank foamthat fell from Columbia's external tank during launch and struck the orbiter'sleft wing. The impact pierced Columbia's heat shield, leaving the spacecraftvulnerable to the searing heat of reentry and hot gases that entered the wingand ultimately destroyed the shuttle.
"I'll neverforget where I was when we lost Columbia," Griffin said, adding that thememories of lost astronauts were strong today. "I will never be able to forgetwhere I was when we lost Challenger; I had a couple of friends on that flight."
STS-114 wastagged as NASA's first of two test flights to evaluate new tools and techniquesto enhance shuttle flight safety and prevent another Columbia-type accident.The 14-day spaceflight, lauded by astronauts and mission managers as wildlysuccessful, delivered tons of vital supplies and equipment to the InternationalSpace Station (ISS), as well as tested three heat shield repair methods,installed new space station hardware and included the first-ever orbital repairof a shuttle's tile-covered belly by an astronaut.
"Eileenmade it look like a cakewalk," NASA's space operations associate administratorWilliam Readdy said of the conclusion of STS-114.
Readdyadded that NASA's second return to flight mission, STS-121 aboard Atlantis,will pick up where Discovery left off.
"It's goingto be really hard to top this mission," Griffin said.
Marring theapparently spotless record of Discovery's successful STS-114 flight is the foamdebris loss seen during the shuttle's launch.
NASA guidedmuch of its return to flight effort and about $200 million to reduce foamshedding during launches to harmless proportions. What was missing was a flighttest, Griffin said, which engineers now have from Discovery's launch.
Imagery andvideo from new cameras aboard Discovery's external tank, the orbiter itself andISS crew photography found evidence of at least five instances of unacceptablylarge foam pieces separating from the tank, NASA officials said.
"I thinkthat now it's clear what it is that we need to go work on," said Bill Parsons,NASA's space shuttle program manager. "Today we honored the Columbia crew;we've brought the Discovery crew home safe."
Some of thefoam debris seen in Discovery's launch fell from ramp largely coated inhand-applied foam, a region that engineers had questions but ultimatelybelieved was safe. Griffin has assigned a "tiger team" to study the issue, butwhether the foam debris problem can be solved in time to mean the Sept. 22opening of Atlantis' current launch window is in doubt and shuttle officialshave pledged to address the problem before the next orbiter lifts off, NASAofficials said.
"We'regoing to try as hard as we can to get back in space this year because we have abig construction project we're working on, and we need the shuttle to do it,"Griffin said, referring to the need to complete the ISS before the shuttles areretired in 2010. "We're not going to go until we're ready to go."
Despite theapparent success of Discovery and the STS-114 crew, more return to flight workis slated for the STS-121 astronauts before NASA can resume major constructionof the ISS.
"It's morelike a relay race and the torch is now passed to Atlantis and the STS-121crew," Readdy said. "Now we have some data to work with, and for the first timein the shuttle era, we've got a very solid place to start."
An initialreport on NASA's STS-114 foam debris investigation is expected to be presentedto ISS program manager William Gerstenmaier--tapped by Griffin to oversee thestudy--later Tuesday, NASA officials said.
Despite twoweather wave-offs from KSC landings, Discovery's return to Earth wentrelatively smoothly, flight controllers said. Discovery's clean bill of health--gainedthrough orbitalphotography and in-flight heat shieldinspections--and a favorable weather outlook at Edwards made the decisionrelatively simple, they added.
"It waspretty straightforward," said LeRoy Cain, ascent/entry flight director forSTS-114, of the decision. "It was a great landing and I'm sure Eileen [Collins]will be happy with it."
Cain saidthere were some technical anomalies, such as an instrumentation glitch withpart of an orbiter auxiliary power unit system, burnt out landing strip lightsand a ground-based microwave beam, but they were only minor hitches and all hadredundancies.
During theshuttle's descent, Collins handed the controls over to STS-114 pilot JamesKelly for about 20 seconds to give him experience at the helm, he added.
AfterDiscovery rolled to a stop and the hatch opened, Collins and her crew walkedaround their spacecraft for a brief inspection before speaking with reporters.
"We broughtDiscovery back in great shape," Collins said. "The crew was very anxious towalk around and see what the outside looks like and it looks fantastic."
Afternearly 14 days in space - mission elapse time stopped at 13 days, 21 hours, 33minutes and 38 seconds--Discovery's landing what as an exciting and successfulflight, she said.
"This is awonderful moment for all of us to experience," Collins said.
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