Nearly two years after Columbia shattered in the sky, NASA still has no way of repairing the kind of holes that could doom another shuttle, space agency officials acknowledged Monday in their latest status report on the return-to-flight effort.
The development of patches for the shuttle wings and other vulnerable locations is proving far more difficult than imagined just months ago and, along with devising a way for astronauts to inspect their spaceship in orbit, represents “one of the most challenging and extensive return-to-flight tasks,” the 268-page report said.
Nonetheless, NASA continues to aim for a May or June liftoff of Discovery and contends it has dealt with all 10 remaining return-to-flight recommendations put forth by the Columbia accident investigators.
An oversight task force will look at NASA’s progress during a public hearing next week in Alabama. Five other recommendations already have been met by NASA to the task force’s satisfaction.
Concern about foam
A piece of foam insulation that broke off from Columbia’s external fuel tank tore a hole between 6 and 10 inches (15 to 25 centimeters) in the left wing during liftoff last year, and exposed the spaceship to the searing atmospheric gases of re-entry.
NASA said it is aggressively pursuing repair techniques for the reinforced carbon panels that line the edges of the shuttle wings, but did not yet have a completion date. Engineers are struggling to come up with patches that would stick to the panels during the intense heat of re-entry and create a smooth surface.
As for the silica glass fiber tiles that cover much of each shuttle, engineers initially thought they had a good putty-type repair method on hand. But vacuum testing has indicated the material foams and bubbles, which could ruin such repairs in space.
More ground testing is needed, said shuttle program manager Bill Parsons. He said the ultimate trial will come during the first two post-Columbia missions, both considered test flights not only for repair and inspection techniques but also for the redesigned fuel tanks.
Whatever patches are available at the time will be flown for testing, Parsons said Monday.
Certified methods not required
He said NASA had followed the Columbia Accident Investigation Board’s direction to do its best regarding repair options. The board did not require certified repair methods in order for launches to resume, he said.
“We have continued to put the best and brightest that this agency has to offer on this. We’ve used every resource this agency and this nation has to work on this. We’ve made a lot of progress,” Parsons said. “There are some issues that we still need to resolve, but we still have some time to go resolve that.”
If the damage to Discovery was serious and could not be fixed, the seven shuttle astronauts would have to move into the international space station — their destination — and await a rescue mission by Atlantis.
“That’s the last-ditch thing we want to do,” said deputy shuttle program manager Wayne Hale. “The No. 1 thing we’re going to do is prevent damage from occurring by making sure things don’t come off the external tank, and that’s where we’ve focused most of our effort.”
NASA’s three remaining shuttles have been grounded ever since Columbia ruptured over Texas, and all seven of its astronauts were killed, on Feb. 1, 2003.