NASA to Fix Door Cracks, Delaying Shuttle Mission

NASA is sending the shuttle Discovery from the launching pad back to the hangar to repair cracked door hinges, a move that will delay a planned March military mission by up to two months, it was announced Thursday.

The agency’s top officials decided to go ahead with the repairs even though tests indicated that Discovery probably could fly safely with the cracks.

“Prudence calls for us to go back and fix it,” said William Lenoir, head of the National Aeronautics and Space Administration’s spaceflight program.

Discovery was supposed to lift off on the year’s first shuttle flight around March 9. Its seven astronauts were to conduct research for the Pentagon, obtaining data to be used to develop sensors to pinpoint enemy missiles.

“If there was a national defense or some emergency reason why we needed to go fly, I don’t think any of us would have any hesitation to go fly this bird,” Lenoir said. “We’re being conservative.”

The hinges are original shuttle parts and there are no spares. New hinges probably will be made to correct the problem, Lenoir said.

Robert L. Crippen, director of the shuttle program, said that Discovery should be ready to fly in late April or early May.

It was a disappointment for NASA workers, who watched as the space agency’s two other shuttles were rolled back to the hangar last year because of hydrogen fuel leaks.

Six flights were completed in 1990, three fewer than planned. Seven missions are scheduled for this year, but Crippen said that one probably will be dropped.

The aluminum hinges are located on two doors on the belly of the orbiter that must close tightly over fuel line connections after the external fuel tank drops off. If the doors are not fully closed, a weak spot is created in the shuttle’s heat shield skin and the heat of re-entry could destroy the vehicle.

Three of the four hinges have cracks on the mechanism that opens and closes the doors. The cracks were discovered last week during a routine inspection at the launching pad.

Chester Vaughan, chief engineer of NASA’s spaceflight office, said he is “reasonably comfortable” that the doors would work properly in orbit. But he said NASA could not take that chance without knowing exactly when or how the cracks occurred.

Engineers believe one of the larger cracks occurred when a signal was sent to one of the doors to close while it was latched open, Lenoir said. Another may have been caused by a nut caught in a door mechanism, he said.

Columbia also has cracked door hinges, but the cracks are tiny. Atlantis’ hinges appear to be fine.