Feb. 1, 2003

Macon Co. NASA Vet Eyes Tiling

- Asheville Citizen-Times
By staff report
© Copyright 2003 Asheville Citizen-Times.

FRANKLIN - Columbia would have undergone chain-reaction disintegration from the intense heat and speed of re-entry to Earth if the protective tiles were damaged, a Macon County man who helped design and test the orbiter said Saturday.

"If the heat shield let go, it would peel off," said former NASA employee Al Ledford. "After that, it's curtains. It only takes one stress point. When the first piece comes off, that's it."

During Columbia's launch Jan. 16, a piece of insulating foam on the shuttle's external tank came off and was believed to have hit the left wing.

Ledford spent 11 years with NASA before returning to Franklin in 1971. He worked at Ames Research Center at Moffitt Field Naval Air Station in California building and testing the scale models used to create the Columbia orbiter. He machined the models, experimented with materials to determine which could best withstand heat and helped conduct tests in a tunnel that simulated the conditions of re-entry.

Columbia's orbiter, Ledford said, was a safe and effective design that shed heat even better than the previous Apollo orbiter, which the Macon County man also helped design.

"They wanted one that would fly like an airplane," Ledford said of the decision to redesign the Apollo orbiter. "It has been safe for all these years."

Other scientists seemed as shocked as anyone Saturday at seeing the space shuttle Columbia fall from the skies over Texas only minutes away from a safe landing in Florida.

"It's difficult to comprehend that this would happen during this phase of the shuttle flight," said Fred DeJarnette, an aerospace engineer at North Carolina State University and director of the N.C. Carolina Space Grant Consortium.

DeJarnette initially thought a reporter was calling him Saturday about the Challenger disaster in 1986, when the shuttle exploded shortly after liftoff. "I turned on the news, and said, `Oh my gosh, it's Columbia.' ''

After 42 years of space flight, re-entry had become routine as the shuttle glided from orbit through the Earth's atmosphere, protected from the friction and high heat by 20,000 ceramic shields. DeJarnette and the N.C. State program had helped with computer programs to determine the heat load in the early days of the shuttle program.

"It's still too early to speculate" about what happened, said DeJarnette. "In that part of the re-entry there are relatively high aerodynamic loads and high heating rates. There are just so many possibilities of what could go wrong."

Ralph Roberts, an Asheville science-fiction author and former NASA engineer, quickly discounted the possibility of terrorism since the shuttle was traveling so fast and so high. "What made me really think was that insulation that came off during lift-off. Columbia is our oldest shuttle. I'm afraid something happened on the takeoff that affected the re-entry."

No science can devise a fail-proof machine, said Michael Ruiz, a physics professor at UNC Asheville. "It's like driving a car. Something can happen to anything mechanical. You try and check everything and do your best to minimize the danger, but in reality, accidents do occur," said Ruiz.

DeJarnette said the disaster could have a "considerable influence on space research. It may speed up the research for a replacement for the current space shuttle."

After the Challenger disaster, NASA halted all shuttle flights for two years. That won't be an option now with astronauts currently in orbit on the International Space Station, said Paul

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