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NASA Test Shows Foam Could Be Culprit
Ben Hutchings writes "The BBC has a report on an impact simulation that aimed to recreate the impact of insulating foam on Columbia's wing. The result was a large hole that probably could not be repaired in orbit even if it was known about."
Thanks for the great comment, mod this up please, it makes a great point. The math and the physics don't work. This looks a lot like NASA doesn't really know what happened for certain, has found a plausible idea, and to appease the public with an "answer", has concocted this experiment. I think we'll start to see some real answers about what really happened with better proof in time.
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Right after the shuddle incident I remember reading something to the effect that the foam issue is politically charged. Basically, in an effort to be PC, administrators decided, against the wishes of engineers, to replace CFC based foam for a more environmentally friendly non-CFC based foam that wasn't as durable/performant.
Does anyone remember or know anything about this?
I can't verify the claims (or find the article for that matter), but it does seem odd that there were no known/published problems (AFAIK) with the foam for 2 decades...
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Why are they firing the foam at 500 mph? I haven't seen a good explanation of where they get that figure from.
As far as I can see, I'd imagine that the foam falls from the fuel tank/booster onto the shuttle wing. The rate of fall should be only the relative acceleration that the shuttle experiences during the fall. (Since both foam and shuttle are presumably moving at the same speed when it detaches from the launcher)
So the total acceleration should be the acceleration of the shuttle (max 3G at liftoff according to a couple of web sources) plus normal gravity - call it 4 G. At most, the foam could fall the full 56 meters of the shuttle/booster/tank height (and most likely substantially less than that).
So, a quick (and probably hideously wrong) calculation based on v^2=2 * Accel * Distance shows that the end velocity of a body falling 56 meters at 4g should be about 33 meters/second, or 119 kph (74 mph)
Anyone know where I've screwed up on this?
The point is engineers chose to use a type of foam that was inferior for environmental reasons. I can't tell you why the engineers ignored the evidence of the foam problem, but switching to the environmentally friendly foam made the problem a lot worse, and yet they continued to use it. That seems irrational, usless you conclude they were more interested in saving the environment than saving the astronauts.
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