A University of Missouri-Rolla researcher who uses a new technique to detect subtle defects in materials is now using that method to study foam samples similar to the insulation used on NASA's space shuttles.
Dr. Reza Zoughi, the Schlumberger Professor of Electrical and Computer Engineering at UMR and director of UMR's Applied Microwave Nondestructive Testing Laboratory, is directing the project for NASA, which asked him to evaluate samples in the days after the Space Shuttle Columbia tragedy. According to media reports, a piece of insulation that appeared to break off of Columbia and hit its heat-protecting tiles is one area of investigation into why the shuttle broke apart on its descent Feb. 1.
This is the first time NASA has considered using this particular method, known as near-field microwave nondestructive evaluation (NDE), to test shuttle materials, Zoughi says. If successful, the effort could result in a new, more thorough approach to testing the foam insulation and other composite materials used on space shuttles prior to launching.
UMR's Applied Microwave Nondestructive Testing Laboratory is one of the few facilities in the nation to conduct microwave NDE, says Zoughi. He adds that more common forms of nondestructive testing techniques, including ultrasound, X-ray, and visual and optical testing, may not work as well for foam or other composite materials used to insulate space shuttles. Most established testing techniques were designed to evaluate metals, he says, and others are limited by the thickness or porosity of the materials.
NASA contacted Zoughi a few days after the Feb. 1 Columbia disaster and asked him to evaluate a sample of foam similar to that used as insulation material for the shuttle. His "extremely preliminary" investigations showed the microwave NDE technique's potential for detecting indications in the materials, so NASA sent him more samples to evaluate.
Microwave NDE has been used to evaluate other materials, from composites to concrete, Zoughi says. His earlier work with the process includes work for the Federal Highway Administration to detect cracks in steel bridges and Navy-funded research into composite materials. His research has also been funded by the National Science Foundation and several governmental agencies and industrial groups.
Because microwave NDE is such a new approach, its use is not widespread. "We're just beginning to see some commercialization of it," says Zoughi. "We still have to make most of our own prototypes."
NASA has provided a $30,000 grant for the initial studies. If the preliminary research with NASA proves successful, UMR may be called upon to develop a prototype device for examining shuttle insulation or other materials.
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