Science and Technology News

Thursday, November 11, 2010

Discovery's Ground Umbilical Carrier Assembly Removed

Overnight, crews removed space shuttle Discovery’s ground umbilical carrier assembly, or GUCA, which includes the flight seal, the 7-inch quick disconnect, or QD and the carrier plate, known as the GUCP, as they continue working to investigate the leak.

Teams performed an initial inspection of the flight seal and quick disconnect prior to sending them to labs for a thorough inspection. Data collected from the initial inspections will be evaluated today by the investigation team. Engineering saw some areas of interest that are being further evaluated. Based on this evaluation, crews could be ready to install a new GUCA on Friday.

During removal of external tank foam insulation, technicians identified two cracks on a section of the tank’s metal exterior. The foam cracked during draining operations following Discovery’s launch scrub on Nov. 5. The cracks were found on the stringer, which is the composite aluminum strip that forms the section between the liquid oxygen tank and the liquid hydrogen tank. The cracks were found at the top of one of the stingers beneath the area of foam that cracked during tanking and are about nine inches long. The cracks in the stringer moved the metal outward sufficiently to dislocate the foam. Engineers are reviewing images of the cracks to determine the best possible repair method, which would be done at Launch Pad 39A.

Crews have repaired similar cracks during external tank production by installing a second piece of aluminum for reinforcement on top of the cracked area before replacing the foam insulation. This piece frequently is referred to as a "doubler."

Exact schedules and repair options still are being evaluated.

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