NASA technicians uncovered a fourth crack on the space shuttle Discovery this weekend, but despite the setback, the launch is still set for the November 30 timeframe.

The latest crack was discovered as NASA officials tried to repair Discovery in the wake of a hydrogen leak and previously known cracks. Those leaks and cracks, as well as inclement weather, delayed the shuttle's launch several times earlier this month. By November 5, NASA decided to push it until at least November 30.

Cracks have been uncovered on the shuttle's stringers, which are 21-foot-long support beams. There are 108 stringers located on the exterior of the external tank - known as the intertank.

"Over the weekend, technicians removed a section of one of the stringers that had two, 9-inch cracks in it. Last Friday, during foam removal and inspection of adjacent stringers to the one with the 9-inch cracks, technicians identified a crack about 3-inches long on the left-hand adjacent stringer," NASA said in a Monday statement. "Further foam removal revealed one additional corresponding crack on the same left-hand adjacent stringer. Technicians plan to remove that section of the stringer Monday night. They'll also install a new section of metal, called a doubler because it's twice as thick as the original stringer metal, on the stringer that had the 9-inch cracks."

Senior managers will meet on November 22 for a launch status briefing to go over repair work and launch prep. An exact target launch date has not been set, but NASA is still "supporting an attempt in the upcoming launch window that opens Nov. 30," the agency said.