[wretchard]

Do you have any sense of whether the foam hardens, if only briefly, when cooled by the cryogenic tank? The foam blocks appear compact before striking the underside of the left wing but is reduced to spray or powder after impact. I am just wondering how hard I need to project a piece of foam to pulverize it on impact. Also, the foam itself would not necessarily have struck the wing along its full surface area. If the fragment struck along its edge, the entire kinetic energy would have been imparted in a very small area, like an icepick. An icepick, even lightly struck can cause cracks in brittle surfaces which later propagate. Everyone who has sailed knows that the wind can capture a large amount of energy and impart it to a sail. What are the vortices like between the tank and the wing. They could well have provided the critical kinetic energy needed to crack the tiles.

[The Great Satan]

All beyond my ken, I'm afraid. I'm inclined to believe the program director when he says they evaluated the risk and considered it not a safety issue, but obviously it is all a bit of a suspicious coincidence.