- The Washington Times - Tuesday, November 22, 2005

NASA is hopeful that its next shuttle mission will launch in May, providing the agency can solve the dangerous problem of insulating foam falling off the fuel tank.

The most recent shuttle flight was the STS-114 mission in July. It was launched after about 2 years of downtime resulting from the Space Shuttle Columbia disaster.

Had everything gone well with Discovery on the STS-114 mission, the next flight, the STS-121 mission, would have been in September. But as Discovery was launched, a camera mounted on the rocket spotted a piece of foam, weighing nearly a pound, fall off the shuttle’s external fuel tank.

A 2-pound piece of foam that fell off Columbia and struck the shuttle’s wing caused the accident that killed seven astronauts during re-entry on Feb. 1, 2003.

The foam that fell off Discovery caused no damage but embarrassed NASA, which had been saying for more than two years that the tank was improved and the problem corrected. The space agency said the issue must be resolved before another shuttle launch.



The external tanks are manufactured at NASA’s Michoud Assembly Facility in New Orleans. The plant was affected by Hurricane Katrina.

“We did lose some time in our resolution of the foam-loss problem,” space shuttle program manager Wayne Hale said. “The estimates are anywhere from one to three months of lost time.”

After the July mission, an external tank originally scheduled for Discovery and another tank planned for a later mission were shipped from Florida back to Louisiana.

While in Florida, one of the tanks had been filled with super-cold liquid oxygen and hydrogen propellants and pressurized as part of a pre-flight test. Because of issues that arose during the tanking tests, NASA elected to use another tank for the STS-114 mission.

Engineers said this meant that, for the first time, NASA had the opportunity to thoroughly reinspect a tank that has been used in the tests.

“We’re very fortunate to have a before-and-after look-see at it so we can compare what happened,” said John Chapman, manager of the external tank project. “We’ve discovered nine small cracks, two of which are visible on the surface [in the tank that was used for the tanking test]. They’re just barely visible — very small. We’re in the process of dissecting the [insulating foam] so we can get a good view of the cross section to see what they look like.”

Compared with the tank that was filled, Mr. Hale said, the unused fuel tank “has no indications [of any cracks]. … That’s about as close to conclusive as you get in this business. It appears that the thermal cycle or pressurization is a factor here.”

Other problems from the STS-114 mission were a loosened “gap filler” shim between two thermal tiles and a damaged thermal blanket. These issues also must be resolved before the next shuttle mission, NASA said.

Mr. Hale said: “We have assessed the schedule and all of the elements can support a launch in the May window. But we have not set that as a flight date. We have set our schedules to work to that date, but we are depending on the resolution of the external tank investigation and the reapplication of the foam as the pacing item. The technical progress is going to drive the schedule, not the other way around.”

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