Slashdot Mirror
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
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?
My Webcomic: Asylum on 5th Street
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
It was the prevailing theory of the media. NASA didn't have evidence either way, but now that they've done the testing and looked at the results, it's now the best theory as to what happened.
NPR had a report last thursday covering the possibilities of repair in space. There's a lot of options, from filling the wing cavity with heat-resistent foam to wrapping the wing in titanium which will burn off during reentry (like the heat shields of Mercury, Apollo, etc.).
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.
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.
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.
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!
>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.
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
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."
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
Here's a good link that explains the speed they're using when test firing the foam.
And we're too cheap to give our astronauts some real protection, like thier own escapable lifepod, built into the shuttle's design.
Funny as it might seem, the problem of 'bail out' in space was studied closely in the fifties and early sixties. As usuall, the Encyclopedia Astronautica has more info, of which I have taken some samples from below.
Back in the early days of spaceflight it was envisioned that flying in space would be like flying any other kind of high-performance aircraft. Thought was therefor given to ejecting from a damaged craft, just as you can fom most military jets. They studied a one crew balistic capsule with a weight per crew of 327 kilograms and a six crew balistic capsule, mass per crew 548 kilograms. Breaking away from the ideas of capsules, you had MOOSE; a inflatable heatshield and parachute combination with a weight of 215 kilogram. Paracone was a simular idea, but with an all up weight of 227 kilograms. An derivative of the existing systems for the B-58 lead to EGRESS, with a weight per crew of 370 kilograms.
Despite this promising start, what did NASA come up with for the shuttle when it was designed? Yes, the infamous Rescue Ball!
As you can see, there really is technical reason why NASA shouldn't be able to equip the shuttle with 'lifepods', but another, very real reason. The lightest of the systems I've picked weights just under a quarter of a ton for each astronaut in question. FOr the seven man crew on Colombia, thats just over two tons to haul into space and back again - two tons less cargo. See why the shuttle don't have liferafts? They simply eats too much of the payload. It makes more sence to add more reservefuel to each mission, in order to make sure any shuttle could, if needed, rendevous with the ISS and stay there until a rescueshuttle / several Souyz caspules could be launched to pick them up.
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
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.
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