HOUSTON--NASA's next space shuttle flightwill not launch before Sept. 22 as engineers struggle to understand and fixfoam debris issues with the launch system's external tank, agency officialssaid Friday.
NASA hadtargeted Sept. 9 to launch the Atlantis orbiter on its STS-121 spaceflight, asecond test flight of fixes made in response to the 2003 Columbia disaster. But the external tank foamshedding observed in the launch of the agency's current shuttlemission--STS-114 aboard Discovery set to undock from the International SpaceStation (ISS)--and other mission processing activities have eroded away at thatflight window, which closes on Sept. 26, NASA officials said.
"Untilwe run out of lead time to make the September window, then we'll preserve it,"NASA chief Michael Griffin told reporters during a roundtable discussion hereat Johnson Space Center."If next week, the guys have a "eureka" moment on the foam and say 'yes, weunderstand it'...then we'll go forward."
Griffin hasset up what he called a 'tiger team' of engineers to investigate the foam lossproblem, which is expected to report to ISS program manager William Gerstenmaier next week on their initial fact-findingefforts at the agency's New Orleans, Louisiana-based MichoudAssembly Facility where the tanks are constructed.
Gerstenmaier said he had not reviewed a 2004 internal NASA memo, first reportedWednesday by the New York Times, criticizing quality control some foamapplication techniques. The report cited that engineers "did not do a thoroughjob" of tracking the minute variations in hand-applied foam, the Timesreported.
"It'savailable I'm sure in all the other documentation that the teams are lookingat," Gerstenmaier said. "We'll take that informationand see if there are some things there, again from a technology standpoint orfrom an engineering standpoint that we can use and apply."
DuringDiscovery's July 26 launch, video from a camera mounted to its external tankrecorded several pieces of foam insulation peel away during the ascent. Alarge, 0.9-pound chunk visibly popped free from a ramp previously thought safefrom foam shedding. That chunk did not strike the orbiter, but at least threeother foam pieces that also separated during the launch and were too large tobe considered acceptable, shuttle officials have said.
The foamdebris from Discovery's external tank disappointed shuttle engineers andDiscovery's astronaut crew, given that NASA has spent two and a half years andabout $200 million of the $1.4 billion devoted to its post-Columbia accidentwork toward revamping orbiter external tanks to prevent harmful foam shedding.Shuttle officials said they will not launch another shuttle until theyunderstand and address the foam issue.
A1.67-pound of foam fell from Columbia'sexternal tank during its launch and pierced the heat shield panel lining itsleft wing leading edge. That wing damaged allowed hot atmospheric gases toenter the wing during reentry on Feb. 1, 2003, leading to Columbia's destruction and the deaths of allseven astronauts onboard, investigators found.
Gerstenmaier said that all of the imagery collected of Discovery's launch andsubsequent orbital inspections has given engineers a wealth of data that theycan put toward
"We learneda lot from this flight," Gerstenmaier said. "The nextstep...is to look at the future tanks that are coming and see if there anyapplications from what we learned."
Only thenwill engineers decide whether to modify the external tank for Atlantis, whichstands mated to its external tank-solid rocket booster launch stack in themassive Vehicle AssemblyBuilding at Kennedy Space Center, or shift theorbiter to a complete new tank, Gerstenmaier added.
While the Sept. 22 launch date for Atlantis shaves about twoweeks from its flight window, there are still multiple opportunities to launchthe shuttle within the narrow flight window.
"It's stillgives us four launch attempts toward the end of the window, and still looksgood from a planning standpoint," Gerstenmaier said.
Meanwhile, Discovery's STS-114 mission nearing its completion. The astronauts have completed theirresupply mission at the ISS and are poised to undockfrom the station at 3:22 a.m. EDT (0422 GMT) Saturday.
Discoveryis expected to land at NASA's Kennedy Space Center (KSC) at 4:46 a.m. EDT (0846GMT) on Aug. 8.
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