Re: Excellent point
The expanding cloud of dust may have impinged on the lower end of the SRB and left traces.
Also, the object that hit the shuttle could have come from the upper end of the SRB in the first place.
I think as long as they don't have a way of saving the crew of a damaged shuttle that has reached orbit then they should have a way of determining rather quickly whether to abort a launch. It could cost alot more to re-design the shuttle than to abort a launch.