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Nondestructive Testing Technologies Have New Emphasis for Shuttle Program

By Kathy Hagood
Brevard Technical Journal

While nondestructive testing has always been important in the Space Shuttle program, it's gotten a higher profile and more research and development funding from NASA as the program gears up for return to flight.

Because the Columbia Accident Investigation Board (CAIB) report emphasized the need for new and better nondestructive testing techniques for the human spaceflight program, scientists and engineers at Kennedy Space Center and beyond are being given the resources to focus like a laser beam on developing select technologies.

The CAIB report, released in August, concluded that the breakup of Columbia on February 1 was caused by a chunk of External Tank foam striking the leading edge of the left wing during the Shuttle's ascent on January 16, 2003. If better nondestructive testing techniques had been in place, the disaster potentially could have been avoided.

Increased NASA funding in the wake of the Columbia disaster is allowing ASRC Aerospace
Corp., the engineering development contractor for Kennedy Space Center's University Affiliated Spaceport Technology Development Contract, to expand its nondestructive testing technology efforts.

"Developing nondestructive testing technologies has always been an important part of the contract, but now there's a new emphasis," said John Horan Jr., ASRC's deputy program manager.

The institution of certain valuable technologies, such as laser shearography for testing whether foam insulation is properly bonded to the External Tank, previously was held back by limited NASA funding. Now a steady stream of return-to-flight dollars will allow such critical technologies to be more quickly adopted into standard procedures for the Shuttle program.

"Any new procedure must be tested extensively and refined before it's applied to the Shuttle program," said Dr. Jeff Hooker, a physicist with ASRC Aerospace. Hooker first worked on applying laser shearography to the ET for NASA in 1996. The technology uses a laser beam to create an image of the foam on the ET at rest and one with the foam stressed by sound or a slight vacuum. Changes in the image signal foam debonding.

The Shuttle program has in the past relied on visual inspections to uncover foam defects.

The Boeing Co. has used laser shearography for years to determine debonding of insulation materials on its expendable launch vehicles, said Kevin Hoshstrasser, chief engineer for Boeing Florida Operations.

"The technology was first applied to the Delta III program and now continues to be used in the Delta IV program," he said.

Hooker and his group are also working on a brand new nondestructive evaluation technology application: acoustic sensors for the leading edge of the Space Shuttle's wings.

The new sensor system could be used to determine whether foam and other impacts during launch or on orbit have seriously damaged the leading edge. If significant damage was determined, astronauts could be alerted to make repairs on orbit or another life-saving strategy employed.

"We think the technology has a lot of promise," Hooker said.

Other ASRC Aerospace scientists and engineers are working on other new technologies specifically being developed in response to the Columbia disaster. One is a software program that will allow for three-dimensional analysis of Shuttle launch and ascent imagery.

While certain nondestructive technologies are gaining new interest and respect, hundreds of others have been used for years during Shuttle processing to help ensure astronaut and vehicle safety.

"You need to be able to test materials without having to destroy them," noted Stan Starr, who formerly served as deputy program manager and chief engineer for Dynacs, the company that previously held KSC's engineering development contract. Nondestructive testing methods aren't always high tech, he said.

"When you think about it, a mechanic listening to an engine to detect a valve problem is a nondestructive testing technique," Starr said.

Another example: ASRC chemist Kathy Brooks is working on a simple, yet effective low-tech method of detecting minute hazardous gas leaks during Shuttle processing. Brooks is testing various types of paper and color indicators.

So far, a simple paper used to clean office equipment and vanillin, artificial vanilla flavoring, seem to be working like a charm to detect the tiniest leaks.

"We're always looking for better ways of doing things," Horan said.