Why the Shuttle crashed

So it looks like we were right about damage to the tiles from pieces of foam splitting off the Shuttle’s fuel tank; that’s the avenue that NASA is pursuing now. So the question is why this foam had never been a problem before, but it turns out foam has plagued NASA for 5 years

As recently as last September, a retired engineering manager for Lockheed Martin, the contractor that assembles the tanks, told a conference in New Orleans that developing a new foam to meet environmental standards had “been much more difficult than anticipated.”
The retired Lockheed engineer, who helped design the thermal protection system, said the switch from a foam based on Freon — also known as CFC-11 — has “resulted in unanticipated program impacts, such as foam loss during flight.”

In fact, he noted, the hits to Columbia on that 1997 mission, the same one Katnik studied, forced NASA to replace nearly 11 times more damaged tiles than it had after a previous mission that had used Freon-based foam.
Lockheed spokesman Harry Wadsworth said Monday that the company was referring questions to NASA. “I cannot talk about any past problems with foam or the history of foam,” he said. “We’re not talking about the investigation.”

Despite the concerns, NASA has never described the foam problem as a potential catastrophic threat, but considered it enough of an issue to warrant a series of tests.

In 1999, the Southwest Research Institute, a non-profit laboratory in San Antonio, Texas, fired insulating foam fragments from a compressed-gas gun into thermal tiles and recorderecorded the results with digital cameras. After the Columbia crash, NASA asked the institute not to release those results. The space agency also has tested the foam in wind tunnels and aboard a research jet.

So concerns about the effects of freon on the ozone layer lead directly to the crash of the Shuttle, apparently. You’d think NASA would be able to get some kind of a waiver on this stuff.