NASA Test Shows Foam Could Be Culprit 525
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."
So don't repair it! (Score:2, Insightful)
Eh... (Score:3, Insightful)
Re:So don't repair it! (Score:1, Insightful)
Sound familar? I'll say the same thing I did then (Score:0, Insightful)
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.
My point is that if the piece of foam broke off the the top of the shuttle when the craft was doing many hundreds of miles per hour (like when the ET separates - the last time the foam (covering the ET) is on the shuttle) the air is not dense enough to slow the piece of foam enough to possibly impact the shuttle at hundreds of miles per hour.
If you toss a baseball out of a car window when you're driving at 100 mph the ball isn't going to slow down to 0 by the back of the car. It maybe will loose 100 mph in comparison to the shuttle by the time it decelerates a bit from where it broke off to where it hits the wing. That's not such a big deal.
If the foam or a bird with oxygen mask and pressure suit were hanging about at a few tens of miles above the earth when the shuttle is going this fast this experiment would be realistic.
Just as well (Score:3, Insightful)
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.
This is no surprise... (Score:2, Insightful)
And I'll bet a bee weighs a LOT less than the chunk of foam that hit the Columbia.
Hey, it's not like this was rocket science...just basic PHYSICS, for Pete's sake!
Re:Sound familar? I'll say the same thing I did th (Score:4, Insightful)
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.
I wondered the same thing... (Score:5, Insightful)
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.
Excuse me, but .... (Score:3, Insightful)
The current Thermal Protection System is a dangerous, fragile and unreliable hack that should be thrown away and replaced with a more sensible system using modern materials and technologies that are proven and ready to use now.
--riney
a large hole that probably could not be repaired (Score:3, Insightful)
You'd be amazed what can be repaired if the only alternative is dying.
What makes me sad... (Score:4, Insightful)
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...
Some back of the envelope calculations (Score:4, Insightful)
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.
Re:happens often (Score:5, Insightful)
"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.
Re:850 km/h in 2 seconds? (Score:3, Insightful)
Let's get a few things straight. (Score:1, Insightful)
2. They couldn't have fixed it on orbit (no tools, materials), they couldn't have 'flown to the station, (wrong orbit, no mating adapter)' they couldn't have sent a soyuz (no mating adapter), and they likely could not have gotten a shuttle up in time (literally no time). Do some reading.
3. They didn't know how serious the problem was. The population of know-it-all monday morning quarterbacks on
4. If NASA freaked out everytime there was a problem of that magnitude, as they understood AT THE TIME, nothing would ever get done. I'm not saying they should take risks, or even that they could have gotten to the point where they were sloppy. The bottom line is that space travel is risky, and those people who work on it take it seriously and to the best they can do. It irks me when people who know so little say 'they should have done this or that.' That *is* the reason there is the accident review board. They have the expertise. Let them do their job, and stop thinking you know more than you do.
Re:computer modeling (Score:4, Insightful)
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.
Re:another story (Score:3, Insightful)
How do you get into NASA without passing highschool physics? If I asked these people -- the ones who declared that such an impact was not cause for concern -- what was heavier; a pound of feathers or a pound of lead, what would be their answer?
First a metric conversion issue that dooms a Mars mission now this.
Use stochastic physics (Score:3, Insightful)
The system of 7 equations you mention would more than likely be highly chaotic, meaning the results would be meaningless unless the initial conditions were known to extremely high accuracy. Of course this depends on the Lyapunov exponent of the specific system. I think we're wandering off into irrelevant territory here.
I think what is ticking me off is hearing people say "High school physics disproves this," wildly assuming that high school physics is not oversimplified and actually describes all possible scenarios. I wish these people would wake up and realize that "high school physics" is to physics as integer arithmetic is to mathematics...
Re:happens often (Score:5, Insightful)
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!