The last flight for space shuttle Discovery is looking increasingly likely to be pushed back to next year, as engineers battle to carry out a series of repairs.
The Program Requirements Control Board (PRCB) yesterday reviewed progress repairing cracks on two 21-foot-long, U-shaped aluminum brackets, called stringers, on the shuttle's external tank.
The board decided that more analysis and tests are required, meaning that Monday's planned launch will be rescheduled.
The next launch window opens on December 17th, with a preferred launch time of 8.51 EST. However, NASA says it's not at all confident that it will have been able to resolve all the issues by then.
While there are other possible launch dates later in December, NASA is keen to avoid this. It would mean that Discovery's onboard computers would need to be reconfigured to take account of the change to the new year while actually in orbit.
And a launch in January would be difficult because of clashes with other, unmanned, cargo launches, meaning that Discovery could still be sitting on Launch Pad 39A at NASA's Kennedy Space Center in Florida until February.
The STS-33 mission will see Discovery taking important spare parts to the International Space Station, along with the Express Logistics Carrier-4, an external platform that holds large equipment.
The mission has experienced a series of hitches since announcing an original launch date of November 1st, including a hydrogen gas leak. The latest problems concern the 108 stringers on the exterior of the external tank. NASA says that of the 5,000 stringers used on Discovery's tanks over the last few years, 31 have been found to be cracked.