[_Jim]

I distinctly recall memos outlining observations of 'puffs' from the joints in the SRB's during lift-off ... part of the 'sealing process these rockets go though' was the explanation - and an acceptable risk given the cost of a re-designing the booster.

But, consider this: *no* failurs had occurred of the SRB up until the Challenger accident. None. Zip. Zero.

The appearance of a little smoke from a rocket joint does not indicate a fail or a fault, this was normal for this series of rockets. In fact, it could be consdered analougous to the 'rings' seating in a car - the "o" rings must first seat, after which they seal.

Again the Risk/Benefit aspect must be considered - treat the booster within proper parameters, and, she will perform as designed.

The mistake came when the SRB was operated outside 'her' limits paramets - a temperature below which the "o" ring would not remain pliable enough, where the normally pliable sealing compound became hardened - and failed to seal-in the high-pressure combustion-product gases that form with the SRB. A failure to seal in those gases - allowing them to escape - was the problem ...

[One Sided Media]

You seem to be very knowledgable about the shuttle so I am curious as to what you think most likely caused the destruction of the craft. If you have multiple possible answers can you assign a probability to them? I believe in the Expectancy Value theorem so you should get pretty close if you are actually as informed as you appear.