I don't dispute the idea of moisture getting
behind the scenes,
OT - that was behind my point about possible "micro"-cracks. You've expanded the point quite well, however
The scenario has been revisited by the Board over the past few days, and I am sure you've been following it as closely as I.
The subject is being eruditely discussed elsewhere, and by some who are or were actively involved in the program. As there has been no further interest in this thread in past days, there seems little point in continuing it here. I'll conclude with a couple of recent quotes which I thought were interesting:
"NASA believes the piece of insulating foam detached from a section of the external fuel tank called the bipod. In addition to sprayed-on polyurethane foam, portions of the bipod and other parts of the tank exposed to the highest temperatures also are treated with a silicon-based substance called Super Lightweight Ablator. The concern is whether that material under the foam also broke lose from the giant aluminum tank, which might have added considerable heft to a piece of foam originally calculated to weigh 2.67 pounds."
". . . . Was it ablative material behind the foam? Was it metal behind the foam or was it ice?"
As it should, the investigation is maintaining a wide perspective.