NASA will begin tests on Discovery's external fuel tank sometime after 15 December, the US space agency says.
Engineers are still meeting to determine a test schedule for verifying repairs associated with cracks on the tops of two 21-foot-long, aluminium 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, postponing the planned 1 November launch. The launch has been pushed back to 3 February at the earliest so engineers can determine the root cause of the cracks.
NASA will attempt to replicate the cracks that occurred when loading the tanks to obtain higher-fidelity information about what goes on under the foam during cryoloading, says Bill Gerstenmaier, NASA's associate administrator for space operations. After removing the protective foam and instrumenting the stringers, the foam will be reapplied before filling the tank. Tanking test plans call for recording temperature and strain gauge measurements in the intertank region near the top of the external tank where the stringers are locate.