Well, for sake of argument, say the foam was immobile in space and the shuttle hit it at 2000 mph--hmmm. That's still quite a whack. And then let's say, again for sake of argument, that the glue on the tile on that leading edge hadn't been applied as precisely as it should have been, the tile itself could have been vulnerable.

That said, I really don't expect the gluing to have been a problem--though it certainly has been a past problem--especially with the leading edges on the wings, which were critical points. I would expect the crew that glued to have taken special care with the gluing of tiles onto those leading edges.

I hope the portion of the wing that was recovered today was the left wing...