Stubborn Leak Grounds Shuttle Atlantis Until Fall

NASA’s last-ditch effort to fix an Atlantis hydrogen leak on the launch pad failed Wednesday and the agency had to postpone the shuttle flight until later this year.

NASA engineers, who had hoped to avoid a long delay by quickly repairing the leak while the ship was on the pad, said the shuttle must be returned to the hangar for more work. It had been scheduled for use in a secret military mission next month.

The shuttle Columbia, also being repaired since a different kind of hydrogen leak caused a planned May launch to be scrubbed, will be the next shuttle to fly. It is scheduled for an astronomy mission in September, and NASA officials said they expect it to be ready in time.

The developments came as a space agency team began probing NASA’s most publicized problem: the flawed mirror on the $1.5-billion Hubble Space Telescope.

The team of seven, led by Lew Allen, director of the National Aeronautics and Space Administration’s Jet Propulsion Laboratory, heard testimony in secret at Hughes Danbury Optical Systems Inc., which made the mirror.

The flaw has halved the effectiveness of the telescope, which was put into orbit in April.

Experts had hoped that the problem with Atlantis could be solved with simple launch pad repairs, but the leak reappeared during a test Wednesday and engineers concluded they still did not fully understand the problem.

“We were not able to fix it. We have learned more, so we will roll back smarter,” William Lenoir, head of NASA’s space flight program, said.

NASA will try to launch Atlantis for the classified Pentagon flight in November.

The latest leak, detected when liquid hydrogen was pumped into Atlantis’ external fuel tank, was about the size of the leak detected in two previous tests and was in the same area, a flange in a pipe that carries liquid hydrogen from the tank to the main engines.

Workers tightened bolts around the flange and checked the welds, though engineers said they doubted that would be enough to correct the problem.

Had the spot held Wednesday, NASA would have tried to launch Atlantis in mid-August and Columbia in September. Now, officials intend to get Columbia ready to be moved to the launch pad in early August, shuttle director Robert L. Crippen said.

NASA officials want to get at least one shuttle up before Discovery’s mission in October with Ulysses, a satellite that will explore the sun’s poles. Discovery has a 19-day “window” in which it must lift off or the mission will have to be delayed 13 months.