Shuttle tank foam fixes nearly finished

NASA aims to mate a modified external tank and twin solid rocket boosters next week after repairing foam covers on metal brackets that hold a liquid oxygen feedline on the exterior of the 15-story fuel reservoir.

Now slated to take place next Wednesday, the work will keep the agency on track for the planned Oct. 23 launch of shuttle Discovery on an International Space Station assembly mission.

Lockheed Martin tank technicians from Michoud Assembly Facility in New Orleans today are replacing the final two of four foam covers that had hairline cracks in an internal cork layer.

Managers were concerned that the hairline cracks could cause foam to break free from the external tank in flight and do damage to fragile shuttle heat-shield components.

A chunk of foam the size of a baseball came off one of the aluminum brackets holding the 17-inch LOX feedline to Endeavour's tank during an Aug. 8 launch. The foam chunk ricocheted off a metal strut and damaged adjacent tile near the orbiter's right main landing gear door.

Subsequent x-ray inspections uncovered hairline cracks on four of five foam-and-cork covers on the tank being readied for Discovery's launch. The covers are made of two types of foam insulation and a superlightweight cork ablator.













The hairline cracks were found in the cork layers of the four covers, so NASA managers decided to replace them with foam-only covers. Two of the new covers were fashioned and installed earlier this week. The final two will be in place today and all four will cure over the next several days.

Now inside the checkout cell of the Kennedy Space Center Vehicle Assembly Building, the bullet-shaped tank will be moved into High Bay 1, where a pair of four-segment solid rocket boosters have been stacked atop a mobile launcher platform.

Discovery is in Bay No. 3 of the Orbiter Processing Facility, where technicians are finishing up engine weld inspections to confirm work done during the manufacturing process.

The winged spaceship is tentatively scheduled to roll over Sept. 19 to the 52-story Vehicle Assembly Building, where it will be hoisted off its transporter, lifted over a 16th-floor transom and then lowered onto the mobile launcher platform so it can be mated to the external tank.

The fully assembled shuttle is tentatively scheduled to roll out to launch pad 39A around Sept. 27.

NOTE ON IMAGES: Click to enlarge the NASA images. The top image shows a Lockheed Martin tank technician inspecting a new foam cover on an aluminum bracket that holds a LOX feedline to the side of the tank. The middle image shows a hairline crack found in a layer of superlightweight ablator on one of the foam-and-cork covers. The last shows a technician sanding a metal bracket after a defective foam cover was removed from it. Photo credits: NASA/Jim Grossmann