NASA still plagued with foam problems
Related complication cited as reason for 2003 Columbia explosion
NASA's John Chapman points to problem areas on a model of the space shuttle's external fuel tank.
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(CNN) -- Under mandate to keep space shuttles grounded until its issues with foam insulation are resolved, NASA discovered nine small cracks in the foam coating on an external tank that had been slated for use by space shuttle Discovery, the agency said Tuesday.
Engineers found the cracks while investigating why a large piece of foam broke from Discovery's external tank during its last liftoff. Analyzing the cracks could help NASA understand the causes of foam shedding, which has emerged as a chronic and dangerous problem for the space agency.
"How do these cracks that we've found figure into that? We don't know," said John Chapman, manager of the External Tank Project at NASA's Marshall Space Flight Center. "It would certainly be premature to say the cracks play a factor in that. We don't know that right now. But they might."
A decision was made to ground the entire shuttle fleet even before Discovery returned to Earth on August 10. That mission, designed to improve safety on future shuttle journeys, was the first since February 1, 2003, when the shuttle Columbia broke apart over Texas while on landing approach to Florida's Kennedy Space Center, killing all seven astronauts on board.
Discovery's July 26 takeoff was the first of NASA's "Return to Flight" missions, but engineers determined that the return may have been hasty when a camera showed debris shedding from the orbiter about 2 minutes after takeoff. (Read about Discovery's return home in August)
Digital photographs later showed a gouge in the insulating foam on an external tank, and further analysis determined that a briefcase-sized piece of foam weighing almost a pound had broken away from the tank.
The foam did not hit the shuttle, but NASA officials said it could have damaged Discovery had it come off sooner.
Bill Parsons, who was then shuttle program manager, announced the day after Discovery launched that the shuttle fleet would not fly again until the foam problem was resolved. (Highlights of shuttle history)
Officials expressed hope the problem would be fixed quickly -- a prospect that would have resulted in another launch this year -- but shuttle managers now say they're focused on a May 2006 blastoff. (Full story)
"We're going to get to the practical solution to ensure that we don't lose large amounts of foam off that tank," said Wayne Hale, shuttle program manager. "That's clearly something that we've got to do to fly safely."
Seven months after the Columbia disaster, the Columbia Accident Investigation Board concluded that a 1.6-pound piece of foam separated from the external fuel tank during launch. The foam, which is used to minimize ice buildup when liquid-hydrogen and liquid-oxygen fuels are loaded hours before launch, struck and cracked Columbia's left wing.
Columbia incinerated when, during re-entry, searing hot gases seeped into the wing.
Engineers have said it's impossible to eliminate foam and ice shedding from the tank after launch, but the tanks have been redesigned to minimize the incidence. Before Discovery's July launch, NASA managers said the largest piece of foam they expected to come loose would be about the size of a breakfast muffin.
Discovery was slated to use the tank with nine cracks, which was tested in April when the shuttle was rolled out to the launch pad. However, after tests, shuttle managers decided to switch out that tank with another. The nine cracks in the original tank were observed later.
NASA is still conducting tests to determine if the tank incurred cracks during testing and if the tank Discovery actually used had similar cracks.
"We haven't found any eureka, or smoking gun so far," Chapman said.
Faced with a barrage of questions Tuesday at the Johnson Space Center in Houston, Hale responded that NASA would not "do something stupid" or set an arbitrary date regarding the future of the shuttle program.
"Let me put this in very simple words in plain English. The results of the technical investigation are going to allow us to fly," Hale said. "And the only people, quite frankly, that I get pressure from on launch schedules is the media. OK?"
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