NASA engineers said yesterday that plans to send the space shuttle aloft next May appear to be proceeding smoothly, but designers acknowledged "setbacks" in devising onboard techniques to repair the thermal insulation on the underside of the spacecraft.
Space Shuttle Program Manager Bill Parsons said, however, that having a fully tested and certified repair method "is not a requirement" for the first flight. "Right now I believe we would fly with whatever capability we have at that time," he said.
Parsons also said he was pleased with the progress engineers have made in modifying the external fuel tank to minimize the chance that insulating foam could break off it and damage the shuttle during launch.
It was such an accident that led to the disintegration of the space shuttle Columbia during reentry on Feb. 1, 2003. The three remaining shuttles have not flown since, and NASA for the past year has been working to make them safer, using a set of 15 recommendations from the Columbia Accident Investigation Board.
The agency has "conditionally closed" five recommendations and expects to begin closing the remainder by the end of this month. NASA released a new progress report yesterday, and Parsons and other NASA officials discussed it in a televised news conference.
"Right now there are a number of things we still have to accomplish, but we have a very, very strong chance of making the [launch] window" that opens May 14, he said. The window lasts for about two weeks.
Engineers have focused on the external fuel tank since the beginning of the investigation, redesigning parts of it and developing new techniques for applying its foam insulation.
Parsons said the external tank modifications are "well on track" and NASA engineers expect to ship the first redesigned tank to the Kennedy Space Center by the end of the year. The first post-Columbia flight was recently postponed from March to May because of hurricane damage at Kennedy and other NASA facilities in the South.
Efforts have slowed, however, in developing onboard repair methods for both the thermal protection tiles on the shuttle's underside and the reinforced carbon-carbon on the leading edges of the wings and nose.
Although NASA engineers have long cautioned that these techniques would be difficult to master, officials said earlier this year that significant progress had been made. The latest report, however, backtracked on that view.
"We have had some setbacks," Parsons said. "I would be very surprised if we had a certified repair technique" for the May flight.
NASA has devised a "safe haven" plan to have shuttle astronauts stay at the international space station in case of another accident until a backup shuttle could rescue them.