updated 6/20/2005 9:20:58 PM ET 2005-06-21T01:20:58

Patches that someday could be used to repair damage to the leading edge of a space shuttle's wing will be carried aboard Discovery in the launch planned next month.

The astronauts will demonstrate that in zero gravity they can assemble the patches, which look like flat disks with anchor bolts through them.

The flight will carry 12 patches, differing in their curvature to match different parts of the wing. In later flights, the shuttle will carry 30 to 50 of the patches, which were designed by ATK Thiokol in Utah.

In January 2003, the shuttle Columbia was damaged during liftoff when a piece of insulation foam struck its left wing. At the end of its mission, as Columbia was descending for landing, superheated air burned into the wing and broke apart the shuttle, killing the seven crew members.

Discovery is scheduled to be launched between July 13 and July 31. As with all of the flights, the spacecraft will be powered in part by two solid-fuel booster rockets built in Utah by ATK Thiokol.

Late addition
Thiokol originally was left out of the team that sought a way shuttle astronauts can repair the wing's leading edge, which is made of reinforced carbon-carbon.

"They originally just went to the folks working on the orbiter" for team members, Mike Kahn, Thiokol vice president for Space Launch Systems, said in a recent interview with the Deseret Morning News.

Because the company builds boosters and did not work on the orbiter itself, its experts were not named to the team. However, Thiokol approached NASA "and reminded them that almost all rocket motors have nozzles and the nozzles are made out of carbon," he said.

Thiokol builds nozzles able to withstand the 5,600-degree Fahrenheit (3,000-degree Celsius) heat of rocket blasts. The shuttle's wing, and any patch, must be able to stand up to the 3,000-degree F (1,650-degree C) heat of re-entry.

"We actually have a lot of experience with carbon materials and high temperature," Kahn said. "We thought we could probably adapt some of our carbon materials that we use in nozzles to be a repair material."

Thiokol experts joined the team, and soon the company began testing "dozens and dozens of different carbon materials."

Testing the patches
Within about six months they had found a suitable carbon material, and, for more than a year, experts they have been testing it in NASA arc-jet facilities that simulate the heat of re-entry.

The engineers had to determine how many of the patches, which are 5 or 6 inches (15 centimeters) across, would be needed to fix different-sized holes, and how they would deal with the contours of the wing's leading edge.

The engineers "developed a thinner patch that can actually flex," Kahn said. That allows a patch to be used in several locations on the wing.

An inspection system also will be tried out on the July flight. Using a camera on the end of the shuttle's boom, astronauts will check for damage to the wing or heat tiles before they return from orbit.

If they find a hole in a wing, they will use a patch or patches that conform to the wing's curvature.

An astronaut adjusts the patch to the shape of the wing, holds it in place, then pushes a molybdenum alloy anchor bolt through a center hole in the patch.

The astronaut cranks the bolt with a specialized mechanical screwdriver. Inside the wing, the bolt's two arms extend until they lock into place on the underside of the reinforced carbon-carbon material. A torque setting on the tool indicates when the patch is clamped on tight.

Copyright 2005 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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