Foam Test Bolsters Shuttle Theory

Foam shot at a fiberglass mock-up of a space shuttle wing knocked loose a seal Thursday, providing hard evidence for accident investigators who suspect Columbia was doomed from liftoff by a debris strike.

The investigators suspect a seal along the leading edge of Columbia’s left wing was damaged when a chunk of foam insulation from the spaceship’s fuel tank slammed into it during the shuttle’s launch.

A spokesman for the Columbia Accident Investigation Board, Air Force Lt. Col. Woody Woodyard, described Thursday’s result as “significant” but not conclusive.

Woodyard said more foam-impact tests are planned in coming weeks. “We’ve got to analyze the data and evaluate all the data before we can draw any conclusions,” he said.

In the first and only shot of the day at Southwest Research Institute in San Antonio, a 1.67-pound piece of space shuttle foam insulation was shot at the fiberglass leading edge at 533 mph. The foam blasted through the 33-foot barrel of a nitrogen-pressurized gun toward the pretend panel No. 6 on the leading edge, tilted at a 20-degree angle.

Upon impact, the adjacent seal lifted and pulled toward panel No. 7, leaving an opening about 22 inches long, Woodyard said. The width of the gap ranged from the thickness of a dime to more than a quarter-inch.

All the parts in the abbreviated leading edge were fiberglass and came from the never-launched shuttle prototype Enterprise, which is housed at the Smithsonian Institution in Washington, Woodyard said. In eagerly awaited testing in June, researchers plan to shoot foam at carbon-composite wing pieces that flew in space.

Fiberglass is about 2 1/2 times more resilient than the carbon-composite material that makes up real wing panels and seals, Woodyard said. That would suggest that a real panel or seal would have been damaged even more by a foam strike.

All seven astronauts were killed in the Feb. 1 disaster, just minutes short of their Florida homecoming.

A final report by the board is expected by the end of July.