Historic, Risky Shuttle Repair Planned

Aug. 2–NASA officials on Monday ordered a Discovery astronaut to attempt an unprecedented repair job in space — plucking two slivers of errant fabric from the underbelly of the shuttle that could cause potentially dangerous overheating during reentry into the Earth’s atmosphere next week.

On Wednesday, astronaut Steve Robinson will make his third spacewalk of the mission, but this one will make history. Astronauts have never gone under an orbiting shuttle before, and have never tried to fix a spaceship’s damaged heat tiles during the flight.

If Robinson can’t grip the pieces of “gap filler” — one sticking up between the tiles about an inch and the other about half that much — then he will clamp them with mechanical forceps and snip them off with scissors or a hand saw.

“At the end of the day, the bottom line, there is large uncertainty because nobody has a very good handle on aerodynamics at those altitudes and those speeds,” said Wayne Hale, deputy shuttle director and chairman of NASA’s mission management team. “Given that large degree of uncertainty, life could be normal during entry or some bad things could happen.”

Hale said officials decided to attempt the repair to “set our minds at rest.”

“This is kind of the new shuttle program, the new NASA; if we cannot prove that it is safe, then we don’t want to go there,” he said. “This exceeded our threshold and we needed to take action.”

Sticking up like ragged fingernails, the gap filler might make the temperature on the shuttle’s underside, which is normally about 2,000-plus degrees, as much as a few hundred degrees hotter. That’s because the two pieces might disturb the airflow surging down the shuttle’s underside as it hurtles into the outer fringes of Earth’s atmosphere at 20 times the speed of sound.

Gap fillers are strips of material, about as thick as rigid Venetian blinds, that fill the space between the insulating tiles that protect the shuttle — and its crew — from the intense heat of reentry.

The repair job would be a largely unrehearsed operation that includes some risk that the astronaut might bump into Discovery’s fragile thermal shield and make matters worse.

“That’s something we have never done before, putting a crew member underneath the vehicle,” said Mission Control spacewalk officer Cindy Begley. “They are going to have to be very careful not to damage anything while they are there.

“It’s a fairly simple task,” she said. “We just need to be sure that we are not going to hit the vehicle when we are doing that.”

Robinson will do the job alone, suspended from a mechanical arm extending from the International Space Station, where Discovery is docked. Begley said fellow astronaut Soichi Noguchi will be nearby doing other jobs. The two men were already scheduled to make Wednesday’s spacewalk as part of Discovery’s mission.

Back on Earth, other astronauts were in the NASA training pool practicing how to do the repair procedure — and then sending their advice up to Discovery.

Gap filler protrusions have happened before, but nobody has had a chance to see one to know how far the fabric has stuck out before reentry.

The filler problem is different from what happened to the shuttle Columbia in 2003. Debris from Columbia’s giant fuel tank came off during launch and tore an undetected hole in its wing, causing the orbiter to burn up on reentry. The disaster killed the seven astronauts aboard and shut down the manned space program for 2 ½ years.

During last week’s launch of Discovery, another chunk of foam flew off the tank, but apparently did not strike the orbiter. The space agency quickly suspended further shuttle launches until engineers can come up with a way to stop debris from falling off the fuel tank.

NASA also announced at Monday’s news conference that the shuttle Atlantis — which could be used as a rescue ship — will remain in preparation for its September launch date.

The problems with the gap filler was detected by cameras on the space station during a first-ever “in orbit” inspection of the underside of the shuttle. NASA leaders scrambled to decide whether the glitches needed fixing at all, and if so, how.

Nor do the experts know what might happen if they simply do nothing.

Mission Control staff members “have been working furiously to try to understand” what effect the additional heat might have, mission operation representative Phil Engelauf said at the Johnson Space Center in Houston.

They know the problem has happened on other flights. Some gap fillers have apparently come lose during the bumpy ride from the launch pad to orbit more than 220 miles up.

But because the gap-filler problem has never been seen before the shuttle has landed, technicians don’t know whether the current protrusions are bigger than previous ones.

“We’re not going to be able to give a definitive answer,” Engelauf said.

—–

To see more of The Miami Herald — including its homes, jobs, cars and other classified listings — or to subscribe to the newspaper, go to http://www.herald.com.

Copyright (c) 2005, The Miami Herald

Distributed by Knight Ridder/Tribune Business News.

For information on republishing this content, contact us at (800) 661-2511 (U.S.), (213) 237-4914 (worldwide), fax (213) 237-6515, or e-mail reprints@krtinfo.com.