The CAIB set up a dramatic recreation of the incident in which it used a nitrogen gun to fire a piece of foam at ~500mph at a test panel. NASA was not happy with the idea of the experiment feeling it was a waste of time. There were audible gasps from the crowd of engineers when the foam punched a head-sized hole in the panel. Bingo.

http://www.theatlantic.com/magazine/archive/2003/11/columbia...