Shuttle accident test reveals 'smoking gun'

A chunk of foam insulation fired at shuttle wing parts 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 ship’s destruction during re-entry over Texas in February, but yesterday’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 1.67lb piece of fuel-tank foam insulation shot out of a 35ft nitrogen-pressurised 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 Mr Hubbard, a high-ranking Nasa official.

He 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.”

Yesterday’s test at the Southwest Research Institute best replicated the blow from debris that occurred 82 seconds into Columbia’s lift-off in January.

Nonetheless, Mr 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.