Dave-Platt%LADC@CISL-SERVICE-MULTICS.ARPA (Dave Platt) (03/12/86)
According to what I've heard, the original failure of the SRB seal may very well have occurred on the outside of the SRB, away from the side facing the fuel tank. I believe that the photos of the puff of steam and smoke during the first second of burn indicate that the burnthrough was pointed away from the ET. Unfortunately, once the seal was breached at one spot, the flow of hot gasses would (and apparently did) lead to further erosion of the seal, and the width of the leak increased over time. Eventually the leak burned far enough around the seal to (possibly) begin burning away the SRB-to-ET support structure, permitting the SRB to break loose and collide with the ET. Take a look at the latest issue of "Discover" for one possible reconstruction of the accident, based on sensor data available to date. Disclaimer: the accuracy of this reconstruction (and any other) is subject to LOTS of debate... until the SRB is recovered and analyzed, we won't really know just how badly the seal burned.