NASA Suspends Shuttle Flights, Citing Debris

HOUSTON -- NASA suspended further flights of the space shuttle fleet on Wednesday after determining that a large piece of insulating foam had broken off the external fuel tank of the Discovery shortly after liftoff Tuesday morning, the same problem that doomed the Columbia and its seven astronauts in the last mission, two and a half years ago.

The foam does not appear to have struck the Discovery, so the decision will not curtail its 12-day mission to the international space station, the officials said. But further flights will be postponed indefinitely, starting with that of the Atlantis, which was to have lifted off as early as September.

"Until we fix this, we're not ready to go fly again," William Parsons, the manager of the shuttle program, said at a news briefing at the Johnson Space Center here on Wednesday evening.

The detection of another large breakaway piece of insulating foam is a potentially devastating setback for the National Aeronautics and Space Administration and a bitter counterpoint to the elation of Monday's seemingly perfect launching of the Discovery, a return to flight that was hailed as an inspiring comeback for the space program.

The effort to fix the foam problem had consumed more than two years and hundreds of millions of dollars. NASA identified the area on the tank that shed the latest piece of foam as a risk, but put off redesigning it.

"We decided it was safe to fly as is," Parsons said. "Obviously, we were wrong."

The incident occurred two minutes into the launching, at a point where the atmosphere is so thin that the piece drifted away. The Columbia accident occurred in part because the foam fell off the tank about 82 seconds after liftoff, when the air was much thicker and slowed the foam so the climbing orbiter struck it with great force.

Wayne Hale, the deputy manager of the shuttle program, said that if the Discovery foam had been shed earlier, "we think that it would have been really bad."

Alex Roland, a former NASA historian who now teaches at Duke and is a frequent critic of the space program, said that in some ways the problem was "worse than an unexpected anomaly arising."

"This was the major problem that they were looking to solve," Roland said. "It must be enormously demoralizing to them."

The Columbia and its crew were lost because a 1.67-pound piece of insulating foam that had fallen off the external tank during liftoff crashed through the leading edge of the shuttle's left wing. The resulting hole admitted superheated gases during the shuttle's fiery re-entry into the atmosphere on Feb. 1, 2003.

In response, NASA extensively tested foam and the way it is applied, modified the tank so that it would be less likely to shed debris, and replaced the foam-covered ramps with a heater.

In the incident described here on Wednesday, the new piece of foam -- a hat-shaped chunk as much as 33 inches across at the widest part and 14 inches at the narrow part -- sheared off another ramp on the external tank. It is known as the protuberance air load ramp, which NASA abbreviates as the PAL ramp, and was designed to minimize crosswise airflow and turbulence around cable trays and lines used to pressurize the external tank. The new piece is slightly smaller than the briefcase-size piece that hit the Columbia, Hale said.

Because of the other redesign efforts on the external tank, NASA engineers estimated that no piece of foam would come off the external tank that was larger than three-hundredths of a pound, and said they hoped to see no foam debris larger than one-hundredth of a pound.

While the two other shuttles, Atlantis and Endeavour, are grounded, work will begin on the PAL ramp problem. "We'll put our best people on it," Parsons said, "and we'll figure out something to do."

"I don't know if that's a month, I don't know if that's three months," he went on. "We've got a lot of work in front of us."