Shuttle to Fly Despite Safety Concerns

NASA Officials Note Risk to Crew but Deem It Acceptable

Two top NASA officials said yesterday that despite voting "no-go" for the space shuttle launch because of continuing safety concerns, they have accepted NASA Administrator Michael D. Griffin's decision to fly anyway and do not object to the scheduled July 1 launch.

The officials, chief safety officer Bryan O'Connor and chief engineer Chris Scolese, said they decided not to pursue their complaints because while the safety hazard endangers the orbiter, they accepted Griffin's reasoning that the crew could either repair any damage or wait on the international space station for a rescue flight.

"The crew has the option of" a safe place to go, O'Connor said in a telephone news conference. "That's the difference between loss of vehicle and loss of crew. Even if I disagreed on the loss of vehicle, everyone in the room agreed the risk of loss of crew was acceptable."

The space shuttle Discovery will be the second flight to visit the space station since the shuttle Columbia disintegrated during reentry in February 2003 after foam insulation from the external fuel tank punched a hole in its shielding against intense heat. The program has endured another yearlong grounding because Discovery's tank lost another large piece of foam during the first post-Columbia flight last summer.

News of O'Connor and Scolese's dissent surfaced last weekend during NASA's flight readiness review for the July mission. Both said the shuttle should not fly until engineers redesigned insulation on foam brackets on the external fuel tank to prevent pieces of it from flying off during launch.

Griffin cleared the shuttle after the review, however, telling reporters that he does not agree that leaving these "ice frost ramps" as they are is an unacceptable risk. Nevertheless, O'Connor and Scolese signed the mission's certificate of flight readiness by crossing out the phrase "I concur with proceeding with this mission" and replacing it with "no-go" statements based on the bracket insulation.

Yesterday, however, both suggested that their objections were more procedural, even bureaucratic, than operational, and were designed to register their concerns in a high-level forum so that Griffin would make the final ruling.

"I believed this should be elevated to the administrator, and I felt very confident that he knew the risks with his eyes open," O'Connor said. "If the administrator could accept it, I felt I was not going to throw my badge down. We now go forward to get this vehicle off the launchpad."

The news conference appeared to mark the end of the latest installment in a dispute that began to percolate within NASA last year and has remained unresolved for months.

During launch last July, Discovery's external fuel tank lost a large piece of foam from a ridge of insulation that serves as a windbreak, shielding pressure lines and electrical cables from the buffeting of liftoff. Engineers subsequently determined that the ridges bore deep cracks, a design flaw that could not readily be fixed.

They decided to fly without the ridges after tests showed that their absence did not pose any extra safety hazard.

But eliminating the ridges meant that 37 brackets holding the pressure and power lines would be more exposed during launch and subject to different stresses. Engineers tried to redesign the foam ice frost ramps shielding the brackets, but tests showed the new ramps performed worse than the old ones. Discovery will fly with unchanged ramps on its external tank.

This dilemma has been known in the agency at least since March, was formally presented to a regular weekly meeting of shuttle planners in April and immediately led to an impasse about whether the July launch should occur. Griffin cast the deciding vote then, but the dispute resurfaced in subsequent meetings, ending with the flight readiness review, the last real opportunity to register complaints.

William H. Gerstenmaier, NASA's associate administrator for space operations, said yesterday that the risk posed by the unchanged ramps is "not desirable" but that "we can tolerate it." Still, he and others have acknowledged that they need to change the ramps, but engineers do not have a fix under design.

This means the next several flights, including a possible rescue mission, will use the unchanged ice frost ramps, a policy that could delay plans for a shuttle flight to service the Hubble telescope. Going to the telescope, unlike the space station, does not offer the shuttle crew a safe place to go in the event of irreparable damage. Gerstenmaier said engineers will decide in October when to visit Hubble.