I know this will be off-topic, but this will only be one post. I have been listening for a week now as theories are bandied about, and the media continues to try to play "gotcha" with scraps of technical information to try to prove somehow that some of the smartest engineers in the world were careless, or stupid, or lazy, or negligent in some way. It really leaves a bad taste in my mouth. As an chemical engineer myself (but not one of the smartest in the world), I can appreciate the complexities of the shuttle and all of the potential malfunctions. It amazes me that these engineers like Mr. Dittemore maintain their cool with airhead reporters (Miles O'Brien excluded) asking questions about boundary-layer flow which they obviously were told to ask by some former something-or-other that their news organization has on the payroll. They usually don't understand enough to ask the question. Yes, the shuttle system has flaws, yes, it has design compromises, but it was a horse designed by a committee. And it is all we have for at least seven years, probably, until the Orbital Space Plane enters service, assuming that happens. Anyway, now I feel better. My theory on this disaster, since everyone has one, is that either the debris impact or some other object struck the left leading edge reinforced carbon-carbon panels and damaged them. These U-shaped panels are attached side by side to the front spar of the wing. Today Aviation Week reported that an Air Force telescope saw severe damage to the wing glove are of the leading edge. If foreign object damage punctured the RCC substrate, a plasma jet could enter the leading edge pocket, where the Inconel brackets that hold the RCC panels are located. Inconel X begins to lose its strength at around 1300 F, and the RCC panels reach around 2700 F, I think. The original specs were for the leading edge to withstand a 1-inch puncture on the upper surface of any panel, but no punctures to the lower surfaces of panels 5-13 (middle section) due to the possiblity of plasma flow destroying the attachment hardware. A program was instituted in 1998 to upgrade the insulation to withstand a quarter-inch puncture to the lower surface of panels 9-12, and 1-inch on panels 5-8 and thirteen. This involved Nextel 440 insulation (made by 3M) around the brackets to help deflect heat and plasma flow to protect them. Columbia was to receive this in its just-finished OMDP. I don't know if it received it or not. But my theory (just conjecture) is that plasma penetrated the panel, destroyed some attachment hardware, and the panel came off. This would account for the drag, and the plasma's journey into the wing would destroy the structure and maybe account for the fairly mild heating. As for the sensor loss, I don't know enough about their location or wiring to say. Just venting my thoughts, Sam Milton ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www.satellite.eu.org/seesat/seesatindex.html
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