Shuttle Launch Delayed Until February

December 6, 2010—First space shuttle Discovery was set to launch in November, then December, on its final trip to the International Space Station. But NASA officials announced today that Discovery will take off no earlier than February 3 because more tests and analysis are needed before the STS-133 mission can safely launch to the orbiting space station. The Program Requirements Control Board met Thursday and reviewed engineering evaluations associated with cracks on two 21-foot-long, U-shaped aluminum brackets, called stringers, on the shuttle’s external tank. NASA repaired the cracks and reapplied foam to the exterior of the stringers. Managers decided the analysis and tests required to launch Discovery safely are not complete. They are planning to conduct an instrumented test on the external fuel tank and structural evaluations on stringer test articles to determine if the analysis is correct. Details and timelines for the tanking test are in work, but plans call for temperature and strain gauge measurements in the intertank region near the top of the tank during the test. The test also will verify the integrity of repairs made earlier when two cracked stringer sections and foam were replaced. In addition, the test will verify the integrity of repairs to the Ground Umbilical Carrier Plate, which leaked an unsafe amount of gaseous hydrogen during Discovery’s November 5 launch attempt. The date of the test is under evaluation, but likely will occur this month. Engineers will continue to search for the root cause of the stringer cracks through data analysis and tests, including placement of manufacturing defects in separate stringers to demonstrate structural integrity in an effort to duplicate the same type of failure that occurred in November. NASA will review and analyze the data from the tests before setting a final launch date. Because of Discovery’s delayed launch, the earliest opportunity for the liftoff of the final scheduled shuttle mission, STS-134 on Endeavour, is April 1. During Discovery’s final spaceflight, the crew will take important spare parts to the International Space Station. Discovery will deliver the Permanent Multipurpose Module (PMM), which was converted from the multi-purpose logistics module Leonardo. The PMM will provide additional storage for the station crew and experiments may be conducted inside it, such as fluid physics, materials science, biology and biotechnology.

The cracks on space shuttle Discovery’s external fuel tank have been repaired at NASA’s Kennedy Space Center. The foam cracked during initial loading operations for Discovery’s STS-133 mission to the International Space Station on Nov. 5. The cracks were on two of the 108 stringers, which are the composite aluminum ribs located vertically on the intertank area. Discovery’s next launch attempt is no earlier than February 3, 2011. Photo credit: NASA/Cory Huston The sun begins to rise at Launch Pad 39A at NASA’s Kennedy Space Center in Florida where space shuttle Discovery awaits liftoff on its final flight, STS-133.

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