From: NASA HQ
Posted: Friday, December 10, 2010
Technicians will work this weekend to prepare space shuttle Discovery's external tank for a tanking test planned for no earlier than Wednesday. Because the test hopes to glean a great deal of information, technicians will place 89 instruments including strain gauges to the tank to precisely record movement and temperatures from the tank's ribbed intertank area as it chills and warms again during the fuel loading and emptying process. The tank holds super-cold liquid oxygen at minus-297 degrees and liquid hydrogen at minus-423 degrees. The cryogenic propellants cause the tank to shrink by about half an inch.
The test will help verify repairs associated with cracks on the tops of two 21-foot-long, U-shaped aluminum brackets, called stringers, on the external tank and help engineers determine what caused the cracks in the first place. Technicians repaired the cracks and reapplied foam insulation on the stringers last month.
Managers determined last week more tests and analysis were needed before proceeding with Discovery's STS-133 mission to the International Space Station. Discovery's next launch opportunity is no earlier than Feb. 3 at 1:34 a.m. EST.
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