[bonesmccoy]

Do you have any info on the ET insulation layers?

You seem interested in the "zippering"...an effect that has never been documented or observed on any STS mission to my knowledge.

I'm more interested in the ET insulation composition and the likelihood of NO zippering. The insulation may have damaged one or two areas enough to permit plasma to leak into the wing structure (just as you described). The argument should not hinge on "zippering or not".

It is obvious that the wing overheated. The question is the failure mode so that a better design can be created.

Regardless, if the ET insulation is falling off, that is a greater issue than the TPS. After all, the TPS flew for 100+ missions without failure.

Why is the ET insulation failing now?

Clinton Administration?

[XBob]

1562 - "Regardless, if the ET insulation is falling off, that is a greater issue than the TPS."
How old was that tank? I think it was 5 years old. sitting around, getting hard, collecting humidity, and sun. The venturi effect between the shuttle and the tank literally sucks the insulation off the tank, particularly where this chunk appeared from

"After all, the TPS flew for 100+ missions without failure."

ROTFL
TPS = 100 missions without totally destroying the orbiter, some TPS failed on every mission.

Why is the ET insulation failing now? -

How old is the tank?

[Thud]

I am no longer saying that tile unzippering caused the loss, though it might have. I am saying that tile unzippering was happening along with lots of other things.

[Cold Heat]

I do not see any zipper effect in my model.

What I do see is a important tile that was dislodged by the foam impact. It likely remained in place, held in place by the packing, and fell off later in the flight.

I believe subsequent tile loss was more a result of the heating/destruction of the hull, or door as a direct result of the initial tile loss.

I realize it is a stretch to say that one single tile loss could bring the shuttle down, but the diagrams, and video, along with the timeline, seem to support this undeniably rare and statistically unlikely occurrence.