NASA to Repair Cracks in Discovery's Fuel Tank
Officials at NASA said two cracks found in the space shuttle Discovery's fuel tanks can be repaired while the shuttle sits on the launch pad. Agency officials said they discovered cracks along the foam insulation lining of the fuel tanks. The cracks (one is at least 20 inches long) were found while the tank was being drained after Friday's failed launch attempt.
"This is something we've seen before, something we've repaired before," Kyle Herring, a shuttle program spokesman at Johnson Space Center in Houston, told USA Today.
"They were found on the stringer, which is the composite aluminum ring located on the top of the tank's intertank area," NASA reported. "The cracks are approximately 9 inches long. Engineers are reviewing images of the cracks to determine the best possible repair method, which would be done at Launch Pad 39A."
Fox News reported the hydrogen gas leak was detected at around 7:30 a.m. ET Nov. 5 in a location known as the Ground Umbilical Carrier Plate (GUCP), which is found at the end of the gaseous hydrogen vent arm on the fixed service structure. It attaches to the shuttle's orange external tank. Technicians said because the GUCP's connection to the tank is so important, it has sensors in place to watch for hydrogen leaking, according to NASA.
Launch controllers track the readings from those sensors closely, and when readings are outside the limits, the countdown is halted. After the external tank is drained of its liquid hydrogen and liquid oxygen and cleared of excess hydrogen, technicians can go out and make any repairs or modifications necessary to fix the leak.
The shuttle's planned launch at the end of November, which was delayed after a series of electrical failures and leaks, will be Discovery's last. When Discovery heads to the International Space Station on its final mission, it will be taking with it two key components-the Italian-built Permanent Multipurpose Module (PMM) and Express Logistics Carrier 4 (ELC4)-that will provide spare parts and storage capacity to the orbiting complex. Discovery also will deliver Robonaut 2, which will become the first humanoid robot in space.
While Discovery remains, at the moment, bound to the ground, NASA's John C. Stennis Space Center in Mississippi conducted a successful test firing Wednesday of the liquid-fuel AJ26 engine that will power the first stage of Orbital Sciences' Taurus II space launch vehicle.
The AJ26 engine is designed to power the Taurus II space vehicle on flights to low Earth orbit. The NASA-Orbital partnership was formed under the agency's Commercial Orbital Transportation Services joint research and development project. The company is under contract with NASA to provide eight cargo missions to the space station through 2015.
The test was conducted by a joint operations team comprising Orbital, Aerojet and Stennis engineers, with Stennis employees serving as test conductors. The joint operations team and other NASA engineers will conduct an in-depth data review of all subsystems in preparation for a 50-second hot-fire acceptance test scheduled several weeks from now. A third hot-fire test at Stennis also is planned to verify tuning of engine control valves.