HOUSTON--NASA's next space shuttle flight will not launch before Sept. 22 as engineers struggle to understand and fix foam debris issues with the launch system's external tank, agency officials said Friday.
NASA had targeted Sept. 9 to launch the Atlantis orbiter on its STS-121 spaceflight, a second test flight of fixes made in response to the 2003 Columbia disaster. But the external tank foam shedding observed in the launch of the agency's current shuttle mission--STS-114 aboard Discovery set to undock from the International Space Station (ISS)--and other mission processing activities have eroded away at that flight window, which closes on Sept. 26, NASA officials said.
"Until we 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 here at Johnson Space Center. "If next week, the guys have a "eureka" moment on the foam and say 'yes, we understand it'...then we'll go forward."
Griffin has set up what he called a 'tiger team' of engineers to investigate the foam loss problem, which is expected to report to ISS program manager William Gerstenmaier next week on their initial fact-finding efforts at the agency's New Orleans, Louisiana-based Michoud Assembly Facility where the tanks are constructed.
Gerstenmaier said he had not reviewed a 2004 internal NASA memo, first reported Wednesday by the New York Times, criticizing quality control some foam application techniques. The report cited that engineers "did not do a thorough job" of tracking the minute variations in hand-applied foam, the Times reported.
"It's available I'm sure in all the other documentation that the teams are looking at," Gerstenmaier said. "We'll take that information and see if there are some things there, again from a technology standpoint or from an engineering standpoint that we can use and apply."
During Discovery's July 26 launch, video from a camera mounted to its external tank recorded several pieces of foam insulation peel away during the ascent. A large, 0.9-pound chunk visibly popped free from a ramp previously thought safe from foam shedding. That chunk did not strike the orbiter, but at least three other foam pieces that also separated during the launch and were too large to be considered acceptable, shuttle officials have said.
The foam debris from Discovery's external tank disappointed shuttle engineers and Discovery's astronaut crew, given that NASA has spent two and a half years and about $200 million of the $1.4 billion devoted to its post-Columbia accident work toward revamping orbiter external tanks to prevent harmful foam shedding. Shuttle officials said they will not launch another shuttle until they understand and address the foam issue.
A 1.67-pound of foam fell from Columbia's external tank during its launch and pierced the heat shield panel lining its left wing leading edge. That wing damaged allowed hot atmospheric gases to enter the wing during reentry on Feb. 1, 2003, leading to Columbia's destruction and the deaths of all seven astronauts onboard, investigators found.
Gerstenmaier said that all of the imagery collected of Discovery's launch and subsequent orbital inspections has given engineers a wealth of data that they can put toward
"We learned a lot from this flight," Gerstenmaier said. "The next step...is to look at the future tanks that are coming and see if there any applications from what we learned."
Only then will engineers decide whether to modify the external tank for Atlantis, which stands mated to its external tank-solid rocket booster launch stack in the massive Vehicle Assembly Building at Kennedy Space Center, or shift the orbiter to a complete new tank, Gerstenmaier added.
While the Sept. 22 launch date for Atlantis shaves about two weeks from its flight window, there are still multiple opportunities to launch the shuttle within the narrow flight window.
"It's still gives us four launch attempts toward the end of the window, and still looks good from a planning standpoint," Gerstenmaier said.
Meanwhile, Discovery's STS-114 mission nearing its completion. The astronauts have completed their resupply mission at the ISS and are poised to undock from the station at 3:22 a.m. EDT (0422 GMT) Saturday.
Discovery is expected to land at NASA's Kennedy Space Center (KSC) at 4:46 a.m. EDT (0846 GMT) on Aug. 8.
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