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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."
I was watchinbg something on channel 7 about this, and they mentioned that this happens at almost every shuttle launch. Apparently it happened, but didn't create such a large hole on another shuttle a few months before columbia. I guess they better fix their stuff before they go off blasting into space again. It also showed how everything melted down because of that hole, scary how such a minor thing can cause such disaster
Wasn't this already the prevailing theory? What exactly is news here?
A slightly more detailed article is available from fox news. A couple interesting things noted here that aren't in the BBC article is that this was the seventh and final test, and that in addition to the camera lens popping off, several other guages which were measuring the experiment were damaged from the impact.
I've been following this pretty closely since I live relatively near the Johnson Space Centre here in Houston, and quite a few NASA people come in where I work. I've heard a lot of talk about training the astronauts all to spacewalk, and be able to repair minor damage to the shuttle, but what exactly would they do if the damage was too severe to be repaired? Would a second shuttle have to be launched as a rescue mission? Would they have to just abandon the damaged shuttle in space, since it would be unfit for re-entry? There's a lot of talk of repairs but I haven't heard any predictions for scenarios where repair was impossible.
Perhaps NASA should start looking at new designs with potentially fatal flaws. Have they not been using this design for something like 15-20 years now?
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It'll be interesting to see what the reaction to this failure will be.
Challenger didn't really rock the way we did Shuttle missions because the problems that led to its explosion were not core to how the Shuttles are built -- someone / some process screwed up and there was a relatively reliable way to make sure it wouldn't happen again.
Columbia, on the other hand, was destroyed because the design of the Shuttle is so fragile that once you develop an external problem, you're dead -- since they're using tiles that are individualized, there are no spares they could carry that would help them fix this sort of problem.
Hopefully, this will be a step in the right direction -- either a radical redesign of the Shuttle, or its abandonment in favor of a more robust solution.
No, the Columbia could not have docked with the ISS. The space shuttle was launched into a much lower orbit and would not have been able to propel itself high enough to reach the ISS. That is one of the 'problems' that has been brought up. I believe they are going to put more restrictions on where in orbit the shuttle can go. However, don't take my word for it. It's been all over the news and on Nasa's website.
A quick check on Spacetoday.com points to several good articles ...
SpaceFlightNow article
Florida Today article and it has three video's of the test
Orlando Sentinel article
Washington Post article
Houston Chronicle article
TastesLikeHerringFlavoredChicken
The impact was so violent that it popped a lens off one of the cameras recording the experiment and prompted gasps from about 100-strong astonished crowd.
When I hear of "entertaining" demonstrations to prove a point, I'm reminded of magicians before an audience and furrow my brow.
Is the real "secret" here a less visually spectacular flaw, not in a bodypart but in the design process and it's assumptions?
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It's amazing to think that prior shuttle launches have had foam break off and strike the wing without this happening (according to Discovery Channel). Makes me wonder what was different, perhaps just the size of the foam chunk. It's good to know they finally tested it out to measure the impact. Tragic that people died first. Here's a link to another article on VOANews.com
Does this also account for the the angle at which the foam in the wing? They don't mention it so I thought it was a question worth asking.
My understanding was that the foam glanced off the wing at high speeds and wasn't simply "shot" into it from a right angle. I may be completely wrong (and would love to be corrected) on my misunderstanding.
This obviously wasn't the same kind of foam we use to sleep on when we go camping.
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.
The impact speed and angle were not worst-case, but based on average estimates. Real-life damage could be even worse and we were lucky, lucky, lucky before Columbia.
NASA officials resisted making the reinforced carbon-carbon panel available for destructive testing, because they take 8 months and $800,000 to make.
The X-15 was considered experimental throughout its entire career, and it flew 199 times, which is far more experience than the shuttle program has had.
Can the impact speed be really that fast? Before the piece of foam fell away from the shuttle, it was moving at the same speed. To impact at 850 km (530 miles) hour, the piece of foam would have to slow down 850 km/h during the short distance between falling off and hitting the wing... during 2 seconds or so. Are the numbers really feasible?
All your questions can be answered with the Columbia Loss FAQ. (scroll down to section "VI: Preventative Measures and Rescue Attempts")
Briefly:
They did not have enough oxygen to last for the weeks it would have taken to prep and launch another shuttle.
Even if they could have lasted, there were only two space-rated spacesuits aboard. And STS-107 had no airlock.
STS-107 had nowhere near enough deltaV to be able to alter their orbit enough to dock with the ISS. This is because the ISS is in a weird inclined orbit to allow Russian supply fights to be able to make it to the station.
This wierd orbit is also the reason that no Russian supply fight could have made it to STS-107
All this was argued to death on sci.space.shuttle months ago. The bottom line was that the shuttle was doomed the moment the heat shield was damaged.
The ISS was out - it was on a different orbit and the Shuttle didn't have enough fuel to make the transition.
On the other hand, I have also wondered why the hell they couldn't send up an empty shuttle and bring everyone back on it. Moreover, once the Columbia had been emptied, they could have tried to bring it back with out bleeding off speed using S turns. The Columbia broke apart as it was slaloming and had just loaded up the damaged wing. Had they known the wing was busted, they may have been able to slide slip the whole way in and kept the damaged wing trailing on the backside the whole way down.
All those ideas go out the door when the shuttle manager said "Even had we known, there was nothing we could have done." For that sentiment alone, he deserved to go - it was a far cry from Gene Kranz'es "failure is not an option" attitude when Apollo 13 blew an oxygen tank.
They didn't just pull that number out of thin air. They looked at the film, calculated the distance the foam traveled in one frame, and thus the speed it hit. True, there's some margin of error in that, but there's an awful lot of intelligent people behind that number.
Columbia was in the wrong sort of orbit to be able to rendevous with the ISS, nor was it capable of generating enough delta-v to enter a rendevous orbit.
This is one of the reasons the board recommended that all future shuttle flights (apart from the already scheduled Hubble Servicing Mission), fly to the ISS, or in Orbits that are capable of rendevousing with the ISS.
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.
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From my point of view, this is the most impressive part of the whole thing:
That's an awful lot of testing that's been done for a mere $4.2 million! Last winter I was involved with some testing that cost $500,000 and the result was a little 50-page report. Way to go, NASA! Hooray for SRI!
I read the news story...including the part where they said, "we could do this again, and get a different result".
So, first, how about doing this at *least* three times?
THEN, take the average, and put the damn thing in front of a horizontally-mounted rocket engine, to simulate actual re-entry, and see if it happens...or if, as has happened in the past, the shockwave keeps the heat from penetrating.
Gee, if that happened, then they'd have to go back to looking for another cause...like (google for it) the diehard's analysis that it was stress corrosion cracking in the hydraulic lines that control the elevons. Loosing control of them would rip the wing *right* off.
But then, stress corrosion cracking shold have been caught...*if* they hadn't cut safety inspectors by 75%, and if the managers, in their own meetings, cared more for safety than for "being a team player, and meeting the schedule".
NASA's management strucure needs flattening, anyway - there's maybe 1 chief for 2 indians. Is that sane, to y'all?
mark
Because prior to this accident, the concensus opinion at NASA was that the foamed insulation was low-mass and crumbled easily enough that it didn't pose a threat to the vehicle. In fact, the mixture of foam being used had been in place for five years. In STS-87, the first time it was applied to Orbiter Columbia, foam debris caused 308 hits on the orbiter, some resulting in deep gashes. After changes in the method of application, the foam was rendered more secure, but chunks continued to break off in future flights.
Still, none of those flights exhibited the kind of damage that would lead to the Columbia tragedy until now. It seems perfectly obvious to "monday-morning quarterbacks" that the foam was a problem, but five years of experience suggested otherwise.
>wrapping the wing in titanium which will burn off
The hidden gotcha which you'd need to account for is that if you have bumps or roughness on the wing surface, you may create a little hypersonic shockwave which will create a localized hotspot downwind, potentially hot enough to burn through even the heat-resistant tiles.
A repair would have to be smooth enough to avoid creating more problems than it solved. Lots of computation and testing would be needed.
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
Psst... Shuttle was moving, too. That's the point - the foam fell off and started decelerating due to drag... at the same time, the shuttle was still accelerating due to thrust. The foam still had a vertical velocity, but it was far slower than the shuttle's vertical velocity... basically the wing caught up with the foam chunk.
They "calculated" the speed of the foam chunk by measuring how long (in frames of the high-speed film) it took for the foam to travel a known length (top of shuttle to wing). Not super accurate, but probably within 10%.
-T
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.
Columbia rescue would have been difficult but feasible: investigators
Posted: Sat, May 24 8:33 AM ET (1233 GMT)
Harold Gehman, chairman of the Columbia Accident Investigation Board (CAIB), confirmed Friday that it would have been possible to mount a rescue mission had the damage to Columbia's wing been known shortly after launch, although such a mission would have been very challenging. Florida Today first reported Wednesday that an internal NASA study, performed at the request of the CAIB, showed that it would have been possible to launch Atlantis -- which was being prepared for a March 1 launch -- on a rescue mission as early as February 9 or 10. Atlantis would have rendezvoused with Columbia, whose crew would have conserved supplies and power to stay alive. Atlantis's crew would have then carried out spacewalks to send supplies and extra spacesuits to Columbia, so that Columbia's crew could be transferred back to Atlantis for return to Earth. Gehman said that such a mission would have been extremely difficult and hazardous, particularly because of the danger of falling foam during launch damaging Atlantis as well. Gehman said it may have also been possible to repair the damage to Columbia by stuffing a bag of water in the hole in the wing, then covering it with teflon tape. Even though either option could have been too risky to carry out, their existence contradicts earlier claims by NASA officials that there was nothing they could have done to save the crew. Gehman said those rescue options make decision by NASA not to seek spy satellite images of the shuttle "even more ominous."
back in 1993, british amateur inventor maurice ward created a plastic he called "starlite", which would withstand temperatures of up to 2700 celsius (that of a nuclear explosion). does anybody know what temperatures are reached during reentry, or for that matter, what happened to ward & starlite? i tried googling but didn't find anything interesting.
ed
They figured that falling foam could not be so fast; it isn't in everyday situations.
But common sense only applies to common situtations. In exotic situtions you have to use math and computers. Your basic intuition simply does not work.
And the difference here is that the shuttle was going extremely fast. I don't know the exact speed, but much faster than 850 km/ hour.
The math of this is that air drag is proportional to the square of the speed. On top of this the foam is much lighter than the baseball. So if the shuttle was travelling in say 4000 km / hour (~Mach 4); what will be the speed of the foam by the time it hits the shuttle?
You have to do math and simulations for this one. NASA did, after the disaster, and you should not throw out the results (that the foam had slowed down to say 3150 km per hour) because of your everyday experience with speeds below 100 km/ hour.
Your post is illustrative of how easy these mistakes are to make. In rocket science, you have to think about and calculate everything; because your intution does not work.
Tor
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.
I don't believe that Columbia was capable of reaching the ISS's orbit even if they wanted to. The Columbia has a lot of extra safety equipment since it was the first shuttle and nobody was certain it wouldn't just blow up on the pad. It is heavier than the newer shuttles.
The ISS is in a highly inclined orbit (in order to launch resupply ships from russia the ISS can't just orbit the equator like most normal satellites). As a result only the newer and lighter shuttles are even capable of reaching its orbit.
In order to visit the ISS the shuttle would have to be launched with this in mind from the outset of the mission. A shuttle launched for this purpose could not deploy normal satellites or visit the Hubble. It isn't just a matter of the orbit being the wrong height - it is the wrong inclination as well.
Inclination is the angle the orbit makes with the equator. A zero inclination orbit stays over the equator all the time. A 90 degree inclination is a polar orbit (cruises over both poles and as the earth turns beneath it the orbit crosses every point on the surface of the earth). I think the ISS is around 30 degrees inclination.
To change orbital inclination you need to thrust at a 90 degree angle to the orbital velocity. It takes a LOT of fuel to make anything more than a minor change.
Inclined orbits need more fuel at launch time as well. A zero inclination orbit launched from near the equator has the advantage that on the pad the shuttle is already moving in the right direction with considerable speed (due to the rotation of the earth). All orbits of a given height require the same velocity to maintain. However, relative to the launch pad, an inclined orbit needs more velocity. The worst orbit from this standpoint is a 180 degree inclination - or retrograde orbit. This is one in which the ship is travelling east to west, and not west to east. The ship must take off and spend a lot of fuel just to get down to zero velocity (it starts off with velocity in the wrong direction due to the rotation of the earth), then it has to spend that much energy again just to get to where a 0-inclinction launch starts off. Then it must spend the normal launch energy to get into orbit.
During re-entry all this extra velocity has to be bled off as well. This doesn't cost fuel since friction is doing the work, but it does stress the tiles more.
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.
I have but a single comment to your post, and that is yes it takes weeks to prep a shuttle for launch except in the case of columbia atlantis was on the pad and ready to go for its march launch.
A Bugg
"The result was a large hole that probably could not be repaired in orbit even if it was known about."
Geez, I always thought you could fix anything with enough duct-tape.
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