SAN ANTONIO – A chunk of foam insulation fired at shuttle wing parts Monday blew open a gaping 16-inch hole, yielding what one member of the Columbia investigation team said was the “smoking gun” that proves what brought down the spaceship.
The crowd of about 100 watching the test gasped and cried, “Wow!” when the foam hit — the impact so violent that it popped a lens off one of the cameras recording the event.
The foam struck roughly the same spot where insulation that broke off Columbia’s external fuel tank smashed into the shuttle’s left wing during launch. Investigators had speculated that the damage led to the shuttle’s destruction during re-entry over Texas in February, but Monday’s test offered the strongest proof yet.
“We have found the smoking gun,” Columbia Accident Investigation Board member Scott Hubbard said of the panel’s seventh and final foam-impact test.
The 1.67-pound piece of fuel-tank foam insulation shot out of a 35-foot nitrogen-pressurized gun and slammed into a carbon-reinforced panel removed from shuttle Atlantis.
The countdown boomed through loudspeakers, and the crack of the foam coming out at more than 530 mph reverberated in the field where the test was conducted.
Sixteen high-speed cameras captured the impact, and hundreds of sensors registered movements, stresses and other conditions. The impact was so strong — packing a full ton of force — that it damaged some of the gauges.
“There’s a lot of collateral damage,” said Hubbard, a high-ranking NASA official.
Hubbard said the test results showed it would have been extremely difficult, if not impossible, for Columbia’s astronauts to have repaired such a large hole in orbit. He stressed that the actual gap in Columbia’s wing may have been a bit smaller — or possibly a bit bigger.
“We know that almost surely there was a breach on the order of 10 inches in diameter,” he said. “Here we’ve got one 16, so that’s in the same ballpark in my book.”
He added: “The board’s goal was to connect the dots between the foam-shedding event and the proximate or the direct cause of the accident, and that’s what this whole test program has been about. I think today we made that connection.”
Monday’s test at the Southwest Research Institute — barely beating out an afternoon thunderstorm — best replicated the blow from debris that occurred 82 seconds into Columbia’s liftoff in January.
Nonetheless, Hubbard expressed surprise at the results.
“It was in here,” he said, smacking his fist into his belly. “It was like, `ah,’ like that. It was a visceral reaction. It was shortly followed by `Oh, my God.’ … I felt surprise at how it appeared, such a dramatic punch-through. But it is the kind of damage, type of damage, that must have occurred to bring down the orbiter.”
Two weeks ago, the investigation board identified the blow from the foam as the most probable cause of the accident that killed the seven astronauts. Hubbard said after Monday’s test: “I think foam hitting the wing leading edge of the orbiter at 500 mph is the direct cause.”
The board plans to release its final report by the end of this month. Much of the report “is going to deal with the other types of causes, contributing causes and other elements of the orbiter program over the last 20 years,” Hubbard said.
One month ago, another carbon shuttle wing panel — smaller and farther inboard — was cracked by the impact, along with an adjoining seal. This time, the entire 11 1/2-inch width of the foam chunk — rather than just a corner during previous testing — hit the wing, putting maximum stress on the suspect area.
The five other previous tests in recent weeks involved fiberglass wing pieces taken from the shuttle prototype Enterprise, housed at the Smithsonian Institution. Those, too, were damaged.
Hubbard said it is questionable whether the best set of cameras trained on the shuttle during liftoff would have detected such a large hole, if they had been in focus, and they were not. He declined to say whether spy satellites would have observed such damage, but he noted that it was a black hole in a black piece of reinforced carbon.
During Columbia’s flight, shuttle managers rejected engineers’ request for spy satellite images to ascertain the extent of damage to the left
Among the board’s preliminary recommendations to NASA: improve launch photography, use take spy satellites to check out orbiting spaceships, conduct better testing of wing panels, and devise an inspection and repair plan for astronauts in orbit.
Monday’s test cost $3.4 million.