A group of experts convened by NASA said yesterday that the space shuttle would likely be ready to fly by the currently planned launch date in May or June, but it cautioned that efforts to devise a way to do onboard repair of damaged heat shielding were moving slowly.
"We think that's the long pole in the tent, and it's got to be worked on harder," said Joseph W. Cuzzupoli, technical panel leader of the Return to Flight Task Group. "Their plans are excellent, and they have a lot of work to do. We're following it day by day."
The task group is an independent body established by NASA to monitor its compliance with 15 safety recommendations made by the Columbia Accident Investigation Board after the disintegration of the space shuttle Columbia during reentry on Feb. 1, 2003.
Co-chairman Richard O. Covey said in a televised news conference that NASA has fully complied with six of the recommendations and conditionally "closed" two others. NASA Administrator Sean O'Keefe has said that the shuttle will not fly again until compliance with all 15 recommendations, plus an additional NASA-imposed safety requirement, is complete.
Most the remaining open recommendations "are well on their way . . . [so] we will be able to complete assessments by the end of March," Covey said. Later, he added, "We don't see anything that . . . can't be accomplished to make the May-June launch window."
Since the Columbia tragedy, NASA and the task group have focused on the risks associated with pieces of foam insulation shedding from the surface of the shuttle's external fuel tank during launch and striking the spacecraft's thermal insulation.
The accident board concluded that a chunk of foam punched a hole in the reinforced carbon-carbon heat shielding on the leading edge of Columbia's left wing, opening the spacecraft to destruction by superheated gas during reentry.
NASA originally scheduled a return to flight for this past September but pushed the date back to next March because of problems in constructing an inspection boom with which to examine the shuttle's undercarriage during launch. That difficulty was largely overcome, but hurricane damage at NASA installations in September caused a further delay until May.
Members of the task group were generally optimistic yesterday about NASA's ability to comply with the 15 recommendations. They praised the agency's redesign of the external tank to sharply reducing the risk of foam loss. The new tank is scheduled to be shipped to the Kennedy Space Center by the end of the year.
The group also expressed little worry about NASA's wish to use the international space station as a "safe haven" in which the crew of a damaged shuttle could wait for a rescue mission.
Retired Army Col. James C. Adamson, the task group's operational readiness chief, said NASA could eventually fulfill this requirement -- the only one NASA imposed on itself -- even though the space station is currently short of food.
"NASA won't launch if station can't support" a safe haven, he said.
The panelists expressed considerable concern, however, over NASA's efforts to develop onboard methods to repair both the reinforced carbon-carbon and the thermal protection tiles that cover the space plane's underside.
Adamson said the tank redesign, the inspection boom and new imaging techniques to be used during launch together form a "risk mitigation matrix" that sharply reduces the possibility of foam damage. He expressed confidence that the shuttle could fly in May with "some repair capability."
"Does that meet the intent of [the Columbia Accident Investigation Board]? Or should it restrict our ability to fly?" asked Adamson. "We will have much discussion on that."