SCHRIEVER AIR FORCE BASE, Colo. --
NASA’s manager of Space Shuttle operations visited the base May 22 to discuss what the space agency has learned in the wake of the Columbia accident and how it has returned the shuttles to flight.
The shuttle program asked people in mission control how the crew could detect and repair damage to the shuttle’s ceramic tiles after damage to the Space Shuttle Columbia’s wing caused the craft to break up during re-entry Feb. 1, 2003, Paul Hill said.
“All of those things were considered impossible,” Mr. Hill said. “The guy who
asked us expected us to study it for a few months, come back and say, ‘It’s still impossible; thanks for playing.’ And based on everything we knew then, it did look pretty darn impossible.”
But to fulfill the United States’ commitment to the International Space Station, “impossible” was not an answer NASA would accept.
“The first thing we did was ask ourselves what it would take to look at the outside of the vehicle,” Mr. Hill said. “We get a good look out the window from the ISS, so we right away started looking at the space station’s cameras—cameras the space station already had on board.”
For the cameras to work, the shuttle would have to perform a flip about 600 feet beneath the space station.
“By August 2003 we had perfected the procedure; the astronauts were flying this in the simulator and had gone from ‘There’s no way I’m piloting my orbiter upside down where I can’t see the target,’ to ‘This is an easy thing to do, and I’m ready to fly,’” he said.
NASA requirements also called for locating quarter-inch holes along the nose and the wings. The ISS’ cameras would not work at that resolution, but lasers originally designed as range finders could. A computer animation demonstrated how the laser would sweep across the wings and the nose cap.
“It took us a year to figure out the details just to put the computer animation together," Mr. Hill said. "It took another year to go from animation to a no-kidding, ready-to-go procedure.” Though the requirement later changed to filling .08 inch holes on the wings, the mapping laser still met the need.
As engineers progressed with detecting damage, they also worked on ways to repair the tiles so the shuttle could safely return to earth. Researchers looked at an orange substance originally developed 20 years ago at a cost of $20 million to determine if they could put it to use.
“We came up with material processing solutions and ended up with a burned glass
surface that actually insulates better than tile,” Mr. Hill said. The changes meant that while the substance still bubbled, it would seal properly as long as it did not rise above the tile surface.
When Space Shuttle Discovery launched July 26, 2005, NASA’s astronauts tested the new maneuvers, detection and repair methods. Late in the flight, astronauts went outside the spacecraft to remove a loose flap of gap filler from near the nose.
Although a piece of foam pulled away from the external fuel tank during launch, it did not strike the orbiter. Mr. Hill showed a video of the launch from a camera mounted to the external tank.
“That piece of video, from one standpoint, was a NASA success,” he said. “Without that camera, we wouldn’t have known that happened.”
Discovery is scheduled to launch July 1. It will do so with a newly designed external tank and refinements to detection and repair methods that have been in the works since 2003. Discovery rolled out to its launch pad May 19.
“The mood of the workers (at NASA) is ecstatic,” said Space Shuttle program director Wayne Hale. “This is a great day to see the orbiter roll to the launch pad. Everybody has been working very hard for the last several months to come to this day, and everybody I’ve talked to has been really pleased this has gone forward.”