[ironman]

"A 2 and one half pound chunk of insulation foam struck the underside"

Written with such certainty... Weight is estimate, composition is a guess (could have been ice too), may have struck leading edge...

[ewing]

I agree, the Challenger was caused by ice as well..I think it may have had a role here

[js1138]

The speed is a bit dodgy also, since the foam and spacecraft would be going the same speed. The relevant part of the equation would be acceleration, not speed.