Washington -- NASA managers said 13 Dec that they are now targetting space shuttle Discovery's launch for no earlier than 3 Feb.
Shuttle managers have determined that more tests and analysis are needed on the cracks in the fuel tank parts that caused the insulating foam to crack.
These tests need to be carried out before proceeding with the launch of the STS-133 mission to the International Space Station.
The Program Requirements Control Board met Thursday 9 Dec and reviewed engineering evaluations associated with the cracks on two 21-foot-long, U-shaped aluminum brackets, called stringers, on the shuttle's external tank.
NASA has repaired the cracks and reapplied foam to the exterior of the stringers, but said analysis and tests required to launch Discovery safely are not complete.
It plans 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. A team of engineers and technicians will inspect the tank for evidence of any foam cracking as it would on an actual launch day.
The test also will verify the integrity of repairs to the Ground Umbilical Carrier Plate, which leaked an unsafe amount of gaseous hydrogen during Discovery's Nov. 5 launch attempt. The date of the test is under evaluation, but it is likely to 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 analyse the data from the tests before setting a 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.
PIC: Discovery on the launch pad in November when the leaks and cracks were discovered.