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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."
Wasn't this already the prevailing theory? What exactly is news here?
Well, I hate to sound callous and all, but... if this indeed was impossible to repair then... well, it was probably for the better.
I mean, I can't imagine having seven people up there dying slowly on live TV. That would have been terrible.
What NASA needs to do now is to just replace the shuttle with something better for crying out loud (the Russians have been doing space on the cheap for any number of years. The STS does not really save us that much money) and get on with life.
Why would NASA be shooting the piece of foam at the wing of the shuttle at "about 850 km (530 miles) hour" (sic.)?! The shuttle is going slowly when just taking off in the relatively dense atmosphere of the surface of the earth. As it picks up speed in the thinner upper atmosphere it is also in an environment with less friction.
The initial report that I remembered hearing, within days of the catastrophe, was that the shuttle was already doing around 1900/mph, when the foam detached and hit the wing. It (the shuttle) was probably still greatly accelerating at that point, and devoid of thrust, an oddly shaped, and "relatively" light piece of foam would probably gain some relevant kinetic energy by the time it contacted the wing. I haven't heard any more recent information on the speed of the shuttle at the time of the contact.
Use your head, can't you, use your head,
You're on earth, there's no cure for that - S. Beckett
I still think your question is intereresting, I just don't think the armchair comparisons to a baseball dropped from a car are at all valid.
AccountKiller
It really pisses me off, everytime I read something like that.
You'd be amazed what can be repaired if the only alternative is dying.
These people are capable of launching a spacecraft from a planet whipping around the sun, through continuously changing gravitational fields, for hundreds of millions of miles, and put it down on a spot the width of your city park. They know physics. To put it bluntly, these people are badasses. The last thing they deserve right now is the intellectual equivalent of a 2 year old arguing over politics with Kofi Annan...
The foam strike happened shortly after the point called "Max Q", where aerodynamic loads are highest. Before then, the shuttle's still moving relatively slowly. After then, the shuttle's in thinner air.
Aerodynamic pressure at Max Q is usually quoted as 580 pounds per square foot.
The piece of foam that hit Columbia is usually described as "suitcase sized" and estimated to have been 1-1/2 or 1-1/4 pounds.
One square foot is a really small suitcase, but the foam wouldn't always have been broadside-on to the relative wind. So 1 ft**2 is the right order of magnitude. The ballpark figure for acceleration is then a = F / m ~= 400 g's.
Rounding off, since this is just back-of-the-envelope, 13,000 ft per second per second. 60 milliseconds would suffice to reach the speed used in the test.
s == 1/2 * a * t ** 2. Accelerate at 400 g's for 60 milliseconds and you've gone 23 feet.
The speed they used in the test is the right order of magnitude.
As someone else pointed out, NASA also had film showing the strike and could do frame-by-frame measurements to estimate the actual speed of the chunk.
Ok, I went & read the FAQ you linked to, but you have misinterpreted what it says. It says that the "Lightweight" tank was used on the Columbia. Regarding the "Superlightweight" tanks, it says,
"Since 1998, however, a revised tank model - a 'Superlightweight' tank - has been in use."
The same FAQ says in the next paragraph,
"In addition to the development of the 'Superlightweight' tanks, Lockheed also began using a reformulated lighter version of the inch-thick, spray-on insulation used on all external tanks in the mid-1990s. The switch was made to comply with an EPA mandate to limit ozone-depleting chemicals."
So the new foam came into use on *ALL* tanks (doesn't say 'only superlightweight'), starting in the mid-1990s, whereas the "superlightweight" tank only came into service in 1998.
The FAQ also says that the use of the new "Superlightweight" tank started with STS-91. But the same FAQ talks about the extensive tile damage found on the return to earth of STS-87, and it mentions that the new, 'environmentally-friendly' foaming method was used on STS-87. It also refers to this new foaming method being one of a few possible reasons for the extensive tile damage. STS-87 comes before STS-91 (unless they have some weird numbering system I don't know about), so it couldn't have used one of the new 'Superlightweight' tanks with its 'environmentally-friendly' foam. So it is apparent from this evidence also, that the new foaming method was used with the Columbia tanks.
If you are going to try to refute somebody, and then post a link to your supposed evidence, please read your evidence carefully so I don't have to waste my time responding.
It seems perfectly obvious to "monday-morning quarterbacks" that the foam was a problem, but five years of experience suggested otherwise.
This is exactly the type of bad logic that helped cause the first shuttle tragedy. The dangerous fallacy that "since it's worked N times before" that it "will work N more times".
*Anyone* who is in a man-critical environment can NOT use the simple fact that something hasn't been a problem yet to conclude that it isn't dangerous.
Yes. "Fair and Balanced" Faux news would have us blame the environmentalists for forcing NASA to use unsafe foam.
That makes all the sense in the world. Instead of blaming the engineers who made the decision to launch in the face of overwhelming evidence that:
a) Foam is falling off of the tanks (does not matter WHY)
b) Foam strikes are already shown to cause tile damage.
c) Ice strikes on Atlantis mission in 2000 caused enough tile damage to create a hot-gas breach on re-entry which was non-fatal. (but easily could have been).
These three points show that something was known about the problem and something should have been done. It doesn't matter WHY the foam fell off. It was known to be falling off. The problem was this decision-making process. Not the foam!
These are my friends, See how they glisten. See this one shine, how he smiles in the light.