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The Dow Chemical Company Message Board

  • yahoo yahoo May 12, 2005 3:17 AM Flag

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    • "Wonder why there's been no comment."

      Didn't anyone tell you! It's a Republican Right wing conspiracy to allow GW to go to war with Iraq!

    • Well finally you read the references. Good boy.

      "I further replied by saying that the tiles are not so "fragile" to the impact with an organic foam as your linked organization would have you believe"
      Yes you did say that and the flight inspector for 87 said that is not the case. They saw the cause of the tile destruction from an on board camera. It was foam.

      Now this is the part we can debate, because this is where I start to extrapolate based on my reading and experience.

      Dittemore showed the press the piece of foam, but he did not show that foam under cryogenic conditions. Ever see the demo of a raquetball shattering after sitting in liquid N2. The foam surrounding the tank would be very brittle. Polyurethane foam, that cold would resemble a pumice stone. Not real substantial, but hard enough for two pounds at 100 miles an hour to provide substantial damage to the tiles especially if they are very fragile as the nasa site said. I also noticed that the foam certification testing was done on panels mounted under a jet, not under cryo conditions.

    • Bonehead? Pain? Retired chemist (there's a disqualifier)? Next, you'll call me a nasty name.

      You started by posting links from some organization promoting the falling insulation theory, and most recently posted links saying the answer is not in sight (which I agree with).

      I replied to your first post containing links to with links to disputing the conclusions, and essentially saying the answer is not yet in sight.

      I further replied by saying that the tiles are not so "fragile" to the impact with an organic foam as your linked organization would have you believe, but more significantly that the leading edge where the impact occurred was not composed of those kinds of tiles. Here is what the leading edge is composed of

      The link you provided used the term delicate, and whether that's synonymous with fragile or not, the link's text went on in a context of expansion/contraction, not penetration. Again, it was you cited for the pencil and rain information, not nasa.

      But for the sake of working this through, so what if pencils can be pushed into a tile (and that's still not the material on the leading edge)? The tile is 2" thick, and a dent of a pencil would not break the tile if it were properly adhering. And then I'll ask, so what if some tiles were broken? There were tiles broken, scored and even missing on several missions that returned safely. So the tiles' "fragility" is not a prime suspect.

      Oh, and I know it's only a matter of minutiae, but 750 fps is about 0.7 MACH and double that is 1.4 MACH, which is not in the range of 2-4 MACH.

      The devil is in the details: that's how it is with science and technology. Guess you were in Employee Relations.

    • Questor, does Dow PR still have you on its payroll? Looks like an opportunity for Dow to save money here... Can't wait till the next round of cuts.

      "how fragile are the tiles (a rain drop can deform them at flight speeds, a blunt pencil can penetrate them)"

      In a nutshell, despite the fact that they can withstand thousands of degrees of heat during reentry, they can't withstand physical force very well at all. You can dent them with your fingers with a gentle squeeze. You can poke a hole thru them with a *dull* pencil. Put the Shuttle on a 747 and fly it thru a rainstorm. Guaranteed you'll find tiles damaged by impact with raindrops at airspeed above 250-300mph (insert metric conversion here, natch). Even if you don't run into rain, tiles can be damaged due to airspeed and turbulence.


    • The closest I've come to any allegation is in asking why no comment has come from NASA, to me or in public, regarding my suggestion of finding satellites that were over Columbia during its descent. There still could be substantive reasons for not commenting, so it's way too soon for "allegations".

      But it's not too soon to ask why not.

    • furry

      I haven't made any allegations about tiles and foam and provided a link in my first post with the Program Manager's comments from NASA. Here it is again:

      <<There's no direct information about the size of the foam piece, but Ron Dittemore, Shuttle Program
      Manager, described using 2.67 lb (a conservative, i.e., high end wt) and double the real local air velocity
      (1500 fps vs actual 750 fps) in a failure mode analysis on a system that overestimates failure. The result
      was no failure. This was in a pdf file on nasa's site >>

      I expressed doubt about your rhetorical use of the information on the links, since rain and pencils were not mentioned.

      Even the latest quote you've provided from a post flight inspector does not say anything about rain and pencils, and while it implies things about the foam used for STS 86, the direct information regarding STS 107 is presented in the pdf file I've linked. Moreover, the quote of MACH 2 to MACH 4 is in contrast to the Program Manager's discussion elsewhere in the pdf file, in which he says the vehicle is moving at 2100 fps, but the <local air velocity is more like 750 fps>.

      Frankly, since none of us has access to first-hand information, all any of us can do is interpret what we have in light of our total experience. It was in that spirit that I strongly disagreed with your conclusions, and still do. I don't know that there can be a conclusion at this point, never mind one "jumped to", but in light of the substantial disagrement of sources, it appears more like you've jumped to a conclusion and are now defending it.


      I was wrong, this is the same ball park. Mach 1 ~ 1000 fps.

      Also, further reading, I recommend the following post, for READING and your evaluation, not for arguments with me.
      The evidence that we find on the ground, and evaluating it and testing it, will help us point in the right direction, whether it was something that happened ... during the on-orbit phase, was it something that happened during the entry phase or was it something that happened during ascent and we didn't see it," Dittemore said. "Those are all possibilities.

      "I know a lot of you have focused on the ET shedding of the debris, but we have not. We're looking at all these other areas because they are also possible and we just don't have any evidence to point us in one direction or the other and we are struggling to find that indicator or pointer to help us find that missing link."

      NASA's administrator Sean O'Keefe reported that "there is no favoured theory" about what caused the accident that killed seven astronauts during re-entry on 1 February. "There is no preferred or optimal or considered-more-likely or more probable consequence or cause that we see developing at this stage. Everything is on the table".

    • rat,
      From what I recall, it was soft and more like a blown glass. Wouldn't shatter, but would indent and compress.
      We will have to trust that experts will be evaluating the products and circumstances and make a knowlegable and credible report at some point.
      My feeling is (and it is only my own gut reaction based on the little knowlege I have of procedures and such) is that some folks at NASA made some bad decisions in the days after launch and over the long term life of the shuttle program.
      'Nothing could have been done if it was decided that the shuttle had been damaged?' That statement has got to send up red flags all around!
      'No way of examining the tile inflight?' Seems like poor planning to me (I've got a great idea for a simple remote controlled space camera, do you think they haven't thought of it?).
      NASA is a magnificent organization, but like any bureacracy, budget cuts and political agendas sometimes get in the way. Compound that with the fact that it is run by engineers who might sometimes have trouble thinking outside their equations, and you're bound to have problems now and then.

    • Fuzz
      Having not held one, is the analogy to scintered glass accurate? I am basing that on the site that describes silica fibers being pressed and heated but not fused. That sounds like a great way to diffuse heat, lousy way to provide structural strength. Sorta what the tiles were intended to do, and described as doing.

      As you seem to understand, I am not accepting or rejecting the insulation theory. Metal fatigue/corrosion of the aluminum where the bolted on heatshields also seems plausible at this point. Physical evidence will show that. It will also be interesting to see if the tiles show signs of high heat along the breakage lines. If they do, according to the guy who did post flight shuttle investigations, that would suggest that the damage came prior to reentry. If they do not, that might be inconclusive since breakup may have occurred before annealing of the tile breaklines could occur. NASA folks will know that, not me.

      I do not give in credence to the sabotage/electromagnetic ray/missile etc. I like to start within the bounds of reason and revisit that area as often as possible. The SF photo with the purple streak sounds like it needs to be researched, but I think it will turn out to be a photographic anomaly, not evidence that will help to solve the mystery. (NASA picked up the camera, as part of what I think is turning out to be a very comprehensive, thorough and honest investigation.)

      Thank god the investigation is not being led by questor and persona who latch on to the minutae to draw conclusions.

      As to persona, I do not know, or have any way of finding out if you are right that it was a PO foam. I also have no way of knowing if you are talking of the old or new foam. However, I really would like to see something concrete other than the word of a untraceable webster.

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