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NASA's Foam Test Offers Lesson in Kinetic Energy
Puneet submitted a followup story on the foam test that NASA conducted to get an idea of what sort of damage could be caused by foam falling off the shuttle fuel tank at launch. As it turns out: a lot.
... could be possible terorist weapons :)
Fry: heh, Yakov Smirnoff said it
Leela: No he didn't.
Foam fell off my shelf the other week.
Should I be worried?
foam and southern florida to science. I tend to get flashbacks of spring break.
I'm surprised that the impact was ever taken so lightly. Paint chips drill holes into satellites and birds take down planes, any impact, given the forces involved with such vehicles has the potential to be catastrophic.
Help me become a Porn Star Guru
Everything flying around in space is potrentially dangerous. A fleck of paint hit one of the space shuttle's windows once and caused a surprising about of damage. Based on momentum, it was the equivalent of a bowling ball hitting the shuttle at 60 MPH. Yeah, that's definately dangerous.
It is pretty obvious that these guys are geeks yes?
__
Cheap reseller hosting Action figures dragon
Did they print the wrong picture? The article implies a great deal of damage but all I can see in the picture is the foam object getting destroyed. The wing itself looks completely fine.
"That's when it came home to me what 1/2mv2 means"
This guy is a rocket scientist? I guess that's one stereotype debunked.
I've been wondering this from the beginning of the foam investigations and tests...
They've talked about firing foam samples at wing mockups at hundreds/thousands of miles an hour, 'cause (I think) the Shuttle was flying at that speed when it was hit. But wasn't the foam also flying at that speed? Shouldn't the actual velocity of the foam hitting the wing edge be fairly minimal?
Or are they assuming that the wind drag on the foam chunk would reduce its absoute speed significantly, thus increasing the relative speed with which it hit the wing?
In other words, did the foam fall off and drop, low speed, into the wing, or did the foam flake off and stop dead in the air, then the shuttle ran into it at a huge velocity?
I think when people talk about the foam insulation hitting the leading edge of the left wing of Columbia during the launch phase, they have to consider the following:
1) When the insulation piece fell off it was essentially encased in solid ice, which is a pretty hard material to start with.
2) At the time the insulation fell off, the space shuttle was travelling a couple thousand miles per hour already. That could (in theory) add to the impact force on the wing.
NASA should have tested the insulation foam encased in ice fired at physical simulation of the shuttle leading edge, in my opinion.
"people's intuitive sense of physics is sometimes way off."
No kidding. How could they think a piece of foam shot at over 500 mph would bounce off harmlessly? Nearly everyone knows a penny dropped off the Empire State Building can kill someone- this foam (which is heavier, and is going faster than the penny would be going) would most certainly do damage.
When you don't have a leg to stand on, don't even get up.
...that they've only just performed this experiment. They claimed earlier that foam falling off the fuel tank not extraordinary, and hadn't been a problem in the past. You'd think with the risks involved it might be worth checking out - just in case. The whole point of engineering is that we don't rely on intuition.
If I seem short sighted, it is because I stand on the shoulders of midgets
...than Columbia's as well.
From the article:
The next round of tests in Texas could add weight to the growing consensus about the cause of the accident. Last week's tests used wing panels from the Enterprise, a test vehicle that never flew in space. That craft's leading edge panels were made from fiberglass because the Enterprise never had to face the heat of re-entry.
Foam testing will resume on Thursday with the first effort to fire a chunk of foam at the actual material used on the leading edge of the shuttle's wing. The material, reinforced carbon-carbon taken from the shuttle Discovery, is substantially weaker and less flexible than fiberglass.
A lesson in kinetics indeed. Perhaps it was a micro-meteorite or junk, but based on this data I'd say they've solved it.
Granted, I'm no physics expert, but after hearing that something tore off of the shuttle during take-off and nailed itself I felt like the damage caused by that could have been disasterous. At least now NASA's performing demonstrations showing what kind of force the shuttle actually had to put up with.
"Hell hath no fury like a woman scorned for SEGA. ..."
I suspect that this is just gamesmanship from NASA and G. Scott Hubbard seems to be pretty good at it.
There will always be a chance that something will go wrong, and people will die. If they had to test every last thing like this, nothing would get done.
-Libertarian secular transhumanist
"That's when it came home to me what 1/2mv2 means...the force was equivalent to catching a basketball thrown at 500 miles per hour."
is he serious?? performing a 5 second equation before telling the shuttle to come back could have predicted and prevented this tragedy. i'm glad it's hitting home for him now...too bad he completley forgot his rudimentary physics a few months ago. this is just another in a long line of examples of NASA engineers not being up to par with basic math. (what...yards != meters???)
It's frightening that such a light-weight piece of foam can doom a fantastically complex and brilliant piece of machinery like the shuttle, not to mention the crew on board who are far more complex and brilliant - and the loss of whom is so much more painful. But it's not really a surprise. I mean, if a penny can kill - and it certainly can - then so can a big block of foam, even if it doesn't weigh much.
Unfortunately, dangers such as these are just a part of space flight. It's never going to go away: as someone else posted earlier, birds can bring down planes and that's a mature technology. If space flight ever becomes routine, it will still be filled with dangers - the question is whether or not people are willing to take the risk. From a scientific perspective, we're very, very lucky that so many astronauts are willing to take it to advance our understanding of the world and the universe.
Still, it's really hard to see that shuttle crew lost to a piece of foam. Or a piece of rubber (Challenger). It strikes me as odd that on something as monstrously complicated as the shuttle, the only two complete failures were due to relatively simple components. It also strikes me as a major accomplishment. Anyway...
If a chunk of foam can cause this much damage, what happens if a bird gets in the way?
I know they test-fire birds at the fuselage, but if a bird hits the wing (or rather, if the wing hits a bird) it could cause problems.
They can find ways to ensure that foam doesn't come loose like this in the future, but I don't think they can eliminate the possibility of overflying birds.
Tarsnap: Online backups for the truly paranoid
I didn't know foam could do that much dammage. I should be more careful before I go to Belegarth Practice this weekend.
I'm sure most of the people here reading this article are very respectful of the situation.
Our hearts go out to the families and friends of those who lost their lives.
Yet, that does not negate the human need to use humor (however distasteful) to help overcome the emotions encountered when dealing with tragic situations. [Note that I'm not agreeing with some of the comments here, merely stating opinion.]
I'm sorry that you will be angered by those people whose postings are unfortunately offensive; I can only imagine there will be far more offensive things posted at 0 or below.
Sorry.
...only outlaws will have Nerf guns!!!
"He invoked the physics equation that describes the amount of kinetic energy in a moving object, saying, "That's when it came home to me what 1/2mv2 means." The simple equation says that kinetic energy is one-half times an object's mass times the object's velocity squared, so that even something very light can carry a great deal of force if it is moving fast enough. In fact, he said, the force was equivalent to catching a basketball thrown at 500 miles per hour."
If it's such a simple formula and the facts where known after the shuttle launch, how can the responsible people rely on intuition rather than getting out a 1$ pocket calculator and determine the force of impact? Something's pretty fishy here..
Seven astronauts lost their lives in this tragedy
Yes, and they were aware of the risks when they signed up. Joking or being serious doesn't change the fact they all died.
Trolling is a art,
The most frightening part of this whole story is that the people expressing shock (SHOCK!) at the amount of damage a piece of foam can do at 500+ MPH are actual Rocket Scientists. Is a basic grasp of physics not required for an advanced degree in Aerospace Engineering?
The second most frightening part of the story is that these tests were performed on a mock-up wing taken from the Enterprise (which has never flown) and is made out of fiberglass, a stronger (but much more heat labile) material than the carbon-carbon stuff the leading edge of the actual wing was made from. I wonder how nasty the results will be once they use the real material that failed.
BFL
There's one thing computing teaches you, and that's that there's no point to remembering everything.
--Doug Copland
Amazing these people. Don't we all remember the ol' mv^2 equation? You shoot almost anything with sufficient force it's going to cause damage. To make matters worse I guess the real problem is that the foam gets even harder due to the cold that it's insulating (go figure).
:-}
Next we'll have terrorists near the shuttle launch with slingshots...
--- I wish I could hear the soundtrack to my life. That way I'd know when to duck.
Well, there are a couple things at play here:
1) Materials are stronger at higher strain rates; essentially, the foam can probably remain elastic to much higher stresses when it is being deformed quickly, in a case such as this. To know more, you would want to do a series of high-strain rate tests on the foam to measure it's basic properties. In hindsight, choosing a foam with poor high-strain-rate performance should have been a requirement.
2) The piece of foam they fired was so big that it probably acted as a constriant; essentially, a piece of foam being confined laaterally will have greater apparent strength than one that is not. When a very small piece of foam is fired, this effect would not be present. Scale is important, beyond just increased mass causing increased damage.
It seems so obvious now, but I hadn't thought of these things before. Ideally, NASA would've conducted tests long ago with many sizes of foam hitting many parts of the shuttle, instead of abandoning the tests after seemingly benign results, in addition to basic experiments-- tests of the confined and unconfined foam.
They either knew the risks, and did it anyway, or *didn't* know the risks, and still did it anyway. Respect and grief should go as far as "they rocked, but let's face it - kinda stupid" and "Yeah, sucks for them". Anything else, you'd better be their family, friends or the ghost of an astronaut.
First there's L. Ron Hubbard, now G. Scott Hubbard? Maybe the problem is that they were using Scientology for the first mid-mission damage assessment instead of science? It's all becoming clear now...
I don't have the numbers right here, and I'm too hungover to crunch them out, but I remember a few years back being told by a professor that a penny can't kill someone. It's too light, and the air resistance creates a terminal velocity that prevents it from becoming all that dangerous.
And the empire state building is wedge shaped, with ledges ever couple of stories. There's no way for a penny to even make it to the ground.
Also, it's not the fact that the foam was going 500 mph hour, it's the fact that the shuttle was.
As the other replies have pointed out, I believe also that the foam is moving right, not left. I first mistook the picture as well thinking it was breaking against the dark bordered right side. However if you look closesly, the blue and mustard frame appears to be the structure holding up the wing, and therefore it wouldn't make sense to send the foam from right to left. The braces would get in the way of the experiment.
It has already struck the left side and is just about to roll off the right. The marks on along the top ridge of the wing, just above the "FG#6 Test 1" sign is the damage I surmise they are talking about.
"Last one in is a rotten goblin!" - Kepp
You damned troll. I'm not sure how this got modded up to "2, Insightful", but I am sure it deserves nothing more than "-1, Flamebait." All you have to do is call someobdy a name and say that somebody died in the making of the story and you've got yourself a troll. By the way, my cat died this morning.
Support Israeli punk bands. Man Alive.
can jam pieces of straw into telephone poles and brick one would say "ummm ... Duh".
And even then an F6 on the Fujita scale which is completely inconceivable (if the F5 is the finger of God, this is the "2-stroke 250cc dirt bike of God") would have wind speeds of 319+ MPH
-- Knowing too much can get you killed, but knowing who knows too much can make you rich.
Tufte also examined the Challenger evidence in his excellent book Visual Explanations.
AlpineR
Something keeps bothering me about this foam story -
a piece falls off the tank and slams into the wing causing damage. OK, I can see that.
But what is that hundreds of miles per hour speed we are talking about here?
At the moment, the tank and the wing are BOTH traveling at 500 miles per hour so the RELATIVE speed of a piece (and its kinetic energy) should not be more than few FEET per second!
Anybody who has seen a piece of straw pushed through a tree or other tornado damage wouldn't be a bit surprised by the damage a bit of foam travelling at 500mph would do. I'm surprised the engineers could have missed this. They should know this kind of thing cold.
HOUSTON, June 4 â" The recent test suggesting that falling foam at liftoff could have caused the damage that doomed the space shuttle Columbia was a jaw-dropping demonstration of the destructive power of something so light, a NASA official said today.
/news/press_releases.)
"I thought: `Oh, my God! This is something. This isn't just a light bounce,' " recalled the official, G. Scott Hubbard, the director of the Ames Research Center at NASA and also a member of the independent board investigating the disaster.
Mr. Hubbard watched the test last Thursday at the Southwest Research Institute in San Antonio, and described it in detail to reporters in a briefing here this morning as a prelude to further tests on Thursday.
Before last week's test, many engineers at NASA said they thought lightweight foam could not harm the seemingly tough composite panels, and privately predicted that the foam would bounce off harmlessly, like a Nerf ball. But Mr. Hubbard said the experiment showed that "people's intuitive sense of physics is sometimes way off."
In last week's experiment, the researchers shot a 1.7-pound piece of foam at a mock-up shuttle wing at 531 miles per hour, roughly the speed of the chunk of foam that hit the Columbia wing about 81 seconds after liftoff.
Film of the experiment, released today, shows that the impact of a piece of foam hitting the wing mock-up caused the leading-edge panel to ripple like the surface of a struck gong. (The video is online at caib.us
The foam shattered, with hunks cramming their way into the seam between the panel and an adjoining seal. That opened a long slit in the surface of the wing four-tenths of an inch wide and about 22 inches long â" potentially, more than enough to let in the stream of superheated gases that melted the wing from the inside out as the craft entered the atmosphere on Feb. 1.
Even the researchers setting up the test were unprepared for the sheer force of impact as a wave of energy moved through the inner structure of the wing and sideways along its panels â" in some places, with seven times the force that the researchers had expected. Sensors inside the wing were knocked loose.
Bouncing a small piece of foam lightly between his hands for emphasis, Mr. Hubbard said: "You don't feel this can do anything. But you fire this at 500 miles an hour, and you saw it."
He invoked the physics equation that describes the amount of kinetic energy in a moving object, saying, "That's when it came home to me what 1/2mv2 means." The simple equation says that kinetic energy is one-half times an object's mass times the object's velocity squared, so that even something very light can carry a great deal of force if it is moving fast enough. In fact, he said, the force was equivalent to catching a basketball thrown at 500 miles per hour.
Later analysis of the test panels showed that the stress from the impact shifted the struck panel to the right by one and a half inches, and that the seal, called a T-seal for its shape, was permanently deformed by one-tenth of an inch even after the foam had been removed.
The exact conditions of the actual foam strike â" with extremes of vibration and temperature and near vacuum, could not be duplicated at the test site, so the researchers have had to improvise and try to match the conditions as best they can, Mr. Hubbard said.
Saying that he spoke only for himself and not the investigation board, Mr. Hubbard said that although the experiment "moves us a lot closer to saying that foam can do this kind of damage," it did not rule out other possible causes of the hole in the wing, including small meteorites and debris in space.
At Cape Canaveral, Fla., the chief of the NASA team that is collecting and examining debris from the Columbia said today that its analysis was consistent with that of the independent investigation board. "We have proven, based on the debris alone, where the breach was," said the official, Michae
How is it that "rocket scientists" became the epitome of intelligence?
Any high-school nerd could tell you that *anything* moving 500 mph could put a hole in you.
The videos are here (where the panel visibly ripples after the impact) and here.
The accompanying slide presentation has the details: the 1.7 pound foam block was fired at 531 mph and, where it struck a T-seal between two panels, displaced them and caused a 4/10 inch gap. This fake wing was made of fiberglass, but given the results, a test with actual shuttle wing material from the Space Shuttle Discovery is planned for today.
Here are some of the headlines from news.google.com:
Shuttle Wing Under Gun
Investigator Amazed by Shuttle Foam Force
Foam theory faces pivotal test
Tests Show Foam Causing Wing of Shuttle to Deform
Foam chunk was shuttle's undoing, tests indicate
Why are all the reports I've read on this been so vague about the experimental setup? they all say "foam shot at wing section... did we mention the wing section was made from fiberglass?"
From how far away was it shot? How cold was the wing section? What was the ambient air pressure?
What was the foam shot out of??!?
So a 1.7lb chunk of foam going 500 mph would do SERIOUS damage. Come on! I mean, what kind of physicists are they hiring that can't wrap their brains around this?
500mph = 804,672 m/h = 224 m/s
1.7lb = 0.77kg
from 1/2mv^2, we get...
0.5*0.77kg*(224 m/s)^2 = 19,000 joules of energy!
From a website on the power of explosives...
TNT releases 2.72x10^6 J/kg
So...
g of TNT = (19,000 J/ (2.72x10^6 J/kg) )*1000g/kg = 7g ~ 0.25 Oz
The size of a large blasting cap.
Now, if you asked Nasa if setting off a blasting cap on the shuttle wing would be good or bad, well, I'd think they'd give you an incredulous look and call the FBI on you for being a terrorist and asking suspicious questions.
This back of the envelop calculation MAY be off somewhat. But any engineer who sat down and said "Does this make sense" could have done it on an envelop as a sanity check.
Now, knowing that foam hitting the wing is like setting off a blasting cap on it, perhaps people will realize the dangers of light things traveling very fast...
Hmmm, I wonder how much energy a feather traveling at 0.5C would release...
What bothers me is the 500 miles per hour number. It's irrelevant how fast the foam was moving relative to the ground, only how fast it was going relative to the shuttle wing. And since this liftoff was very non-realativistic, we can use classical kinematics:
This foam was attached to the tank at lift-off, right? That means it was going the same speed as the shuttle at that instant it broke off. THAT means that RELATIVE TO THE SHUTTLE, it accelerated from zero to 500 mph (AGAIN, ELATIVE TO THE SHUTTLE) in the space of 200 ft or so. Well, using the kinematics equation:
Vf^2 - Vi^2 = 2ad
with:
d = (worst case for most acceleration) = shuttle length = 200 ft,
Vi=0
Vf = 500 mph = 733 ft/sec
gives
acceleration = a = (Vf^2 - Vi^2)/2d = 733^2/(.0379 * 2)= 7088245 ft/sec^2 = 220000 times the acceleration due to gravity!
Check my numbers, please, but that seems a little high to be caused by braking due to air resistance.
"Lawyers are for sucks."
- Doug McKenzie
It doesn't change anything, but I think that one is certainly more respectful than the other.
But Mr. Hubbard said the experiment showed that "people's intuitive sense of physics is sometimes way off."
Keep this in mind next time you hear about a "Duh" experiment. Scientists routinely test even the most "obvious" of assertions, because every so often those "obvious assertions" are actually wrong.
There's an interesting article at MSNBC about the "what-ifs..." After the disaster, NASA investigated what could have been done if they knew how badly the shuttle had been damaged during the flight. It's really very interesting -- it discusses how they might have repaired the damage while in space. Brings back memories of Apollo 13. It's a good read.
-David Ziegler
-
I can't stand when the media sells disaster, cable programs like "What Went Wrong?"....
Leave the engineering issues to engineers and scientists. The general public doesn't give a rat's ass about kinetic energy or materials science, they just use it as an excuse to re-live the tragedy over and over.
I suggest you read Slashdot
the address is NYT, isn't it? what happened to "free registratration yadda yadda...."?
Seven astronauts lost their lives in this tragedy and all of the posts I've seen are dumb-assed jokes.
Compared to Challenger, this shuttle loss has been notable for its lack of jokes.Considering how much damage something as small as a paint fleck can do, at high speeds, a 1.5 pound chunk of anything can be dangerous.
Happiness is like peeing yourself. Everybody can see it but only you can feel its warmth.
I thought the purpose of engineering was to make neet gizmos and toys.
Eat at Joe's.
unless fired out of a shotgun at someone or unless you choke on one you were sucking. 'Wanna see what a buck fifty in dimes'll do to your skull?' (later Billy says:) 'Best buck fifty I ever spent'
"can doom a fantastically complex and brilliant piece of machinery like the shuttle"
The more complex a system (the more moving parts, for example), the more susceptible to failure the system is. The complexity of the shuttle's systems (due to its design for reuse within a high-launch-number economy of scale that was never achieved by NASA) Lends itself to failure. No offense, but look at the Soyuz - its a reliable, simple design, and thus its suscuess rate is extreemly high. Of course, it is so simple because the USSR designed it as a nuclear launch vehicle, with low maintenence and launch-tech requirements. And its not reusable.
In the days following the Columbia disaster, I found a reference on CNN where NASA claimed the expected failure rate of a shuttle launch was 1 in 256. The article was pulled very quickly. Due to the pull, I can't dig to find out if they meant 1 in 256 for loss fo the vehicle and crew, or 1 in 256 for Something to go wrong.
man is machine
Next week Nasa has announced the use frogs hitting the shuttle wing at high speeds!
Dude foam weapons are SOOO Fun! When we were kids we wrapped foam around PVC pipes w/duct tape. We had this old couch cushion and used the whole thing to wrap around a 'Bubba Clubba' Holy crap! When that sucker smacked upsid yer head you saw stars!
Eat at Joe's.
Shortly after the accident an astronomer's magazine here in Germany (called "Sterne und Weltraum") came up with this already. They talked about something traveling at 200m/s - the shuttle had a speed of Mach 2 vertical at that time - would be like a human throwing a 1 kg hammer from a distance of a meter at the wing. This simulation is of course much more precise.
Nevertheless, I do not believe that physicists have a bad intuition or feeling for their work but rather were still shocked by the tragedy and it is always hard to rule out something much more unpredictable as space debris or meteorites.
...You're forgetting that the External Tank is filled with liquid oxygen and liquid hydrogen, both of which are liquiefy at temperatures WAY below that of the temperature that liquid water turns into ice. That's why just before launch you can see the ice buildup on the foam surface of the External Tank; there's a well-known picture of the Atlas rocket carrying the Friendship 7 Mercury spacecraft just when it was starting to leave the launch pad, and you can see the massive amounts of ice chunks falling off the surface of the Atlas rocket because one of the fuels loaded was liquid oxygen.
I remember that the day STS-107 was launched it was a pretty cool day, so ice buildup on the External Tank may have been a bit above normal. That means during the first few seconds after launch there would be less ice chunks falling off the tank, and that meant the ice would take longer to fall off, causing a serious foreign object damage (FOD) hazard to the shuttle tiles.
In my opinion, the best way to solve the problem is to use a new and more durable material for the shuttle tiles, something that NASA seriously studied during the late 1980's. This would allow for better heat protection and also is less susceptible to FOD damage from External Tank foam insulation material encased in ice.
Using a 1.609 conversion factor... tsk. 1609 metres and 34.4 cm to the mile, thank you very much! Hmmph nerd indeed. And don't claim you were rounding to four significant figures either, it would still be 3.219x10eX... (But in fairness, I agree with you - lol)
since you asked for it:
NASA: Need Another Seven Astronauts
and
NASA: Need Another Shuttle Also
Chicken breaks Speed Record (And Blasts through 747)
If the bird is obliterated, it's because it's not flying @650MPH.
Didn't you ever watch Jake and the Fatman? He was handy with a pistol, no doubt about it.
So long, michael. Don't let the door hit you...
In a discussion a long time ago, the subject of using popcorn as a weapon came up.
An un-popped kernal at relativistic speeds, gives the energy of a small nuke on impact. In theory at least.
Could we please decide on a measurement system and stick with it?
This illustrates why it may be a good idea to put some money into research of an alternative to the shuttle program. The shuttle program will always face dangers of this type, considering the speeds/forces involved in getting the shuttle into orbit.
Perhaps a program where a spacecraft could actually take off like an airplane and be piloted out of the atmosphere. Even if a large burst of propulsion was needed to get it out of the atmosphere: it would be pulling less G's since it would already be moving with good speed, it would have to do so for less time, and there possibly wouldn't be external systems needed to do it (booster rocket and foam...).
If the official consensus ends up being that the foam caused this, perhaps it will be an impetus for change.
If the shuttle got hit with a fleck of paint during launch, nobody would notice. If the shuttle got hit with a piece of foam in orbit, I think it would likely be destroyed.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
with all the talk of kinetic enrgy - If I took a cessna and sped it up to half the speed of light and shot it at the earth - what would happen? Considering that the speed would be relative to a straight in shot at a continent.
_ _ _ Go for the eyes Boo! GO FOR THE EYES!
Sure it was going at 500 miles per hour but so was the shuttle! I guess next you'll tell me that if I jump up and down on an airplane I will find myself thrust up against the bathroom
--Joey
The tank is coated in a hard foam similar to the polyurethane foam used in insulation.
Do a little experiment yourself here (warning: not for little children : ) Go to the hardware store and find a can of "Great Stuff" foam insulation spray. It's used to fill the holes in walls around pipes.
Now, lay out a plastic trash bag, and empty the entire can onto the bag -- (warning: the stuff expands as it hardens; so, start in the middle of the bag).
Once it hardens, take a look at the result. This is similar stuff, not quite as nice as what they use on the shuttle of course... Also, keep in mind that an entire can of "Good Stuff" is only 12oz. (3/4 lb). You'd need over two cans of the stuff to make a piece the size they're talking about.
Think about that hitting you doing 500 mph...
Of course, however when science is involved you have to detach and look at the hard data. Sometimes a black-humour joke helps.
Trolling is a art,
I just did some rough math and guesswork. It seems the wing took about as much force as if I had driven my Ford Escort into it at 15MPH. That's quite a bit of force!
I wonder how many Volkswagen Beetles that is?
"Sometimes, I think Trent just needs a cup of hot chocolate and a blankie." -Tori Amos on Nine Inch Nails
In a related news item NASA engineers were heard to be lamenting that they have access to million dollar computers that can calculate the question to the universe (the answer is known to be 42) but not one of them has even a $1 calculator. They were also told never to use a pencil and paper or even that tried and true scientific calculation devise, the back of a envelope.
Interestingly the world was heard to say, "These guys are idiots right?"
Sure information wants to be free, but how much are you willing to pay for the packaging?
I can't help but wonder (especially with the airliner industry losing serious money) how much they make regular thourough checks of commercial jets? Especially those old ones that have been running non-stop for the last 25 years.
Almost everytime some jet crashes, and 200+ people die in an instant... they end up not having a clue what happened, covering it up, and move along.
Cocksuckers.
It's actually "impulse", which is a force, calculated by the change in momentum over time. So a 10g piece of foam hitting your spacecraft at 10,000 metres per second, which takes 1/100 second to come to rest (allowing for some deformation) exerts a force of (0.01 x 100000 x 100) = 10 kN. Over an area of a few square millimetres this can do some nasty damage.
When I am king, you will be first against the wall.
These stories of ice covered foam remind me of something...
In one of the NRC labs in Ottawa, they have a "chicken gun" that fires broiler chickens at high velocity into mock ups of aircraft windshields. It is probably an urban legend, but I heard a story that some British engineers decided to duplicate the experiment, and were horrified to find that the chicken smashed a hole clear through the windshield mockup and buried itself in the far wall. They emailed their Canadian colleages to ask what they were doing wrong. The reply was simple: "thaw the chickens first."
But seriously, as the velocities increase, so does the danger. I once saw a picture of the windshield on another orbiter that had been struck by a tiny fleck of paint from an old booster. It looked like it had been struck with a bullet, and had the paint fleck been slightly larger, NASA would have had yet another catastrophic end to a shuttle mission.
If we ever develop a really good propulsion system that can approach light speed, we had better invent deflector shields along with it. As you hit relativisitic speeds, anything you collide with releases energy proportional to an equivalent sized hydrogen bomb. Even molecules become dangerous, and a dust speck would blow a good sized hole in your spacecraft.
My rights don't need management.
You'd be dead.
The foam testing reminds me of a story I read in an aviation magazine a long time ago. In the UK, fighter plane canopies were being impact tested by firing dead chickens at them. The canopies kept breaking. Turns out someone forgot to thaw the chickens.
SCO to Hell
More to the point of this whole thing...
Think about ANYTHING hitting you at 500MPH. DUH?
"Last one in is a rotten goblin!" - Kepp
First, RTFA...
/. before about the idea of ALL factors involved.
"In fact, he said, the force was equivalent to catching a basketball thrown at 500 miles per hour."
THEN
although the experiment "moves us a lot closer to saying that foam can do this kind of damage," it did not rule out other possible causes of the hole in the wing, including small meteorites and debris in space.
What is it about this being a peice of foam that they still can't cop to this being most likely.
If I saw you throw a basketball at my car at 500mph, I would likely stop looking for the "real" cause of the dent!
Even after the experiment and the basic lesson in physics, they still won't say "Yeah, we are keeping our minds open to any new evidence, but right now it appears that this foam strike was the a major factor in the accident."
THERE IS NOTHING WRONG WITH SAYING "Yes, we think this is what caused the damage" If it was instead the basketball that indeed hit the shuttle, the debate about what caused the damage would be wrapping up.
I say major factor, becuase I personally have theorized on
Below is the text of my former post on this idea-
'Under the conditions of a normal return to earth, the shuttle flies on autopilot until it is traveling more slowly than the speed of sound. But pilots train to take the shuttle all the way down in case the autopilot malfunctions, and so it is possible one of the pilots was trying to take control of the yawing craft in its final moments. 'It is relatively easy for the autopilot to be turned off by accident, which in fact happened just minutes before the problems with the Columbia started to become apparent. In the recovered segment of flight deck video of the waning minutes of the flight released by NASA, Colonel Husband is heard to exclaim, "Oh, shoot," and to tell mission control that "we bumped the stick earlier," briefly disengaging the autopilot. He quickly and calmly corrected the error'
What this all leads me to is this, and I have not seen this suggested in anything I have read as an important concern: Is it possible that this accidental disengaging of the autopilot CONTRIBUTED to the loss of the Shuttle? Although the pilots are trained to fly the Shuttle without the Autopilot, if they were unaware that it was turned off then the "minute" adjustments that either one would make would be missed. All accounts I have seen suggest that the slightest details on the approach make HUGE differences in the results. Add to this the fact that it has been reported that the Autopilot, when on, was acting to correct the flight path anomalies caused by the damage outside. If the autopilot is off, then what other consequences were being experienced?
Is it possible that this with the likely outside damage and other factors may have COMBINED have caused the loss of the Shuttle where any issue ALONE would have not? With all the speculation I have seen in the media, I am not sure this is any less of a possibility...
BTW, I personally am not trying to lay blame on the astronauts themselves. Much like a Cruise Control that starts to mysteriously disengage on a vehicle, I would not be surprised if the Autopilot may have "sensed" a disengage as simple as moving the stick, and the pilots assumed that one of them must have done it."
---"What did I say that sounded like 'Tell me about your day?'"---
Well, while Tufte's criticisms are valid, they are also irrelevant. That analysis was for damage to tiles struck by a glancing blow while the accident appears to have been cause by a direct strike to the carbon-carbon wing leading edge. So the key question is not whether those models were wrong, used inappropriately, or presented badly, but why did they model the wrong problem?
Oddly enough, a little over the month before Columbia was destroyed I emailed an engineer friend re long-term probabilities, specifically not the per-mission risk but the likelihood of an unbroken string of successes. An excerpt is below -- comments welcomed.
My thinking was that regardless of the risk of individual mission failure, people are actually interested in the length of the winning streak and absolute number of failures. Humans, especially this one, do have trouble intuitively assessing probabilities.
I believe NASA was considering revising the 1-in-300 to 1-in-500 figure before the accident; unfortunately it now appears to be accurate or optimistic (we need a larger sample to have confidence).
From day one, they have danced around the subject of ice. They just won't talk about it.
The Shuttle's main tank is a huge cryogenic storage cylinder. It is cold, very cold. So cold that they have to insulate it. So cold that atmospheric air will form a sheet of ice on its outsides. So cold that ice formation is monitored before launch. Why won't they talk about this?
The leading portion of an aircraft body and wing is where ice will accumulate in flight. It can collect in amounts large enough to make the aircraft unaerodynamic. Amounts large enough to fall off in chunks. Why won't they talk about this?
The material seen impacting the Shuttle wing has been described as "grayish-white". Ice just happens to be this same color. What color was the insulation? Was it grayish-white too? I doubt it! If the insulation were the same color, how could they visually check against ice formation before launch?
The impression that I am getting (from this article as well as others) is that intuitively the engineers didn't think the foam collision could cause any damage. I haven't seen anything written indicating that there was any past history with pieces of foam striking the leading edge of the orbiter's wings. I have seen articles indicating that foam has struck the underside tiles and damaged one of the landing gear doors and while the tiles were damaged, none in such a way that the shuttle was ever in danger.
I would think that the line of thinking was, when the foam separated, it was moving at the same speed as the shuttle itself. Since the shuttle, at time of impact was at 50,000+ feet, the force of air drag on the foam would be negligible and the piece of foam would approximately maintain its speed.
I seem to remember that it is about 30 feet from the bipod to where the foam struck the orbiter's leading edge, so assuming that the foam travels at approximately the same velocity as when it came off and the shuttle was accellerating at 2.5 Gs, it would take about 1.4 seconds for the foam to hit the leading edge. Using these assumptions, the velocity of the foam at impact, relative to the leading edge, would be 110 ft/sec or roughly 75 mph.
This doesn't sound too bad - after all, it's foam. Getting hit by a Nerf football that has been thrown hard by somebody close by stings, but it won't break bones or even come close to breaking the skin. If you don't think it could do more than bruise you, then it would be hard to accept that the carbon-carbon leading edge of the orbiter could be damaged.
I think that this was the level of intuitive analysis that was done. Unfortunately, it wasn't backed up by any kind of quantitative analysis using known facts (such as estimating the speed of the impact from the film and checking it against the intuitive speed of impact) to test whether or not there were grounds for concern.
myke
Mimetics Inc. Twitter
You energy would be .25E. For a cessna that would be huge....
Slashdotter are stupid and biased.
"What is it about this being a peice of foam that they still can't cop to this being most likely."
Because someone applied the foam, and either the application or the foam, or possibly the process, was faulty.
That leaves someone culpable and exposed to legal action. Micrometeorites, space debris, those are ascts of God.
Welcome to the new litigious society.
Yeah - but what would happen - would it impact the earth? Be harmlessly absorbed by the atmoshpere? Do a tunguska event?
_ _ _ Go for the eyes Boo! GO FOR THE EYES!
Why does the old joke about "which is heavier, a pound of feathers or a pound of lead?" keep coming to mind?
Folks, a small weight moving fast packs a lot of punch. Even foam/feathers/pillows.
Same thing as driving over those orange traffic cones. Drive over a 100 at less than 15 mph, who cares. Plow into a just a few at 100 mph and look at the mess you made of your front end.
Yes, I made this mistake once. It was 4 am, I was paying more attention to the garbage truck I was about to pass than the cones coming into my lane very quickly. I chose hit the cone instead of the garbage truck. Those soft little cones cracked lights, dented my hood, and nearly ripped my exhaust off.
Life moves pretty fast; if you don't stop and look around once in a while, you could miss it. -FB
At the time the foam fell off, the shuttle was still accelerating at full power. The piece of foam also entered the slipstream between the shuttle and the external tank, which is where most of the acceleration came from.
Thank you. I didn't want to be the one to tell him.
I'll add my 0.02. Business rewards the risk takers. Whether they be entrepenuers, or quality assurance managers on shuttle designs. That is until something goes wrong. But that's what risk taking is all about isn't it?
"Last one in is a rotten goblin!" - Kepp
whazzup with that?
Whoever modded this flamebait needs a kick in the teeth. This is funny, dammit!
First of all the foam piece was part of the shuttle. So it broke off and hit the shuttle a little further down. In a "near vacuum" (sp?). So if the piece was traveling as fast as the shuttle before it broke off, didn't have much air resistance to slow it down and hit the shuttle a few tens of feet away how did it accelerate (well, decellerate, same difference, opposite vector direction) to 500 mph less than the velocity of the shuttle?!
Also why are NASA engineers surprised about Ek=1/2mv^2?! I think the reporter meant he didn't think the foam would do much damage, and the NASA guy couldn't think of anything simpler than Ek=1/2mv^2 to explain it to his dumb reporter ass. (sorry, small rant)
I haven't posted in so long, my sig is out of date.
Which is why his result is so totally unbelievable.
"I thought: `Oh, my God! This is something. This isn't just a light bounce,' " recalled the official, G. Scott Hubbard, the director of the Ames Research Center at NASA and also a member of the independent board investigating the disaster. [emphasis added]
pardon me, but doesn't his position as director of Ames Research disqualify him as a candidate for an independant board? This foam study great and interesting, but I can't see how a genuine inquiry into this matter can occur without a true 3rd party.
opinions welcome
shpoffo
Do we know what the Tunguska event caused? Some suspect a UFO entering the earths amtosphere on a bad trajectory. Could this be brought into correlation with a chessna?
I really would've thought that NASA scientists would've had a better grasp on these fundamentals.
I don't know how fast the air friction melts this, but wouldn't foam laden with ice be even worse?
See my journal, I write things there
"What's the hardest test we can rig up to prove this..everybody knows foam isn't going to do anything even at 500 mph."
heh - but it was an "Unidentified Flying Object that caused the event.
Well, Falling maybe - But still...
_ _ _ Go for the eyes Boo! GO FOR THE EYES!
This has nothing to do with anything, other than you trying to show off a cursory understanding of physics.
Moderation: Put your hand inside the puppet head!
Your comparison of a two objects of different masses but equal momentum isn't very relevent. Kinetic energy is the relevent value to look at.
Basic mechanics: Momentum and energy are both values that are conserved. Momentum is m*v, (kinetic) energy is 0.5*m*(v^2). How do these values change in the impact, and what is the result of those changes?
For the sake of simplicity, pretend the shuttle is sitting still in a vacuum and the foam is the only thing moving. Minus some effects of acceleration at the moment of impact, this isn't so bad an assumption. Anyway, the foam hits the shuttle and imparts some of its momentum, such that the total momentum is the same afterward. 1.7kg*500mph of momentum imparted to the shuttle would result in the shuttle moving at 1.7kg*500mph/(mass of shuttle i'm too lazy to look up but is obviously really freaking huge) = negligible. A tiny amount of movement and spin.
Energy, on the other hand, is 1.7kg * (500mph^2). Energy is also conserved, which means that when the foam hits the shuttle the kinetic energy must be absorbed somehow. Since momentum tells us that the change in kinetic energy of the shuttle is small, then most of the energy is absorbed by the material itself. If the energy is sufficient to break the bonds holding the materials at the point of impact together, then they break. The square law is very important here, as it means a very small object going very fast is much more dangerous than a very big object going very slow. In the case of your example, a 1g spec of dirt at 20,000 mph has the same energy as a 1kg block at 632mph. Now that is something you want to avoid.
This difference in momentum vs kinetic energy is why people don't get knocked over backward when they are shot (by most things). The kinetic energy of a bullet is very high and thus damages your body, but the momentum of the bullet is relatively small, and your much larger mass means there is almost no change in your velocity.
Anyway, the lesson is that anything traveling at 500mph has the potential to be dangerous.
The enemies of Democracy are
Then when you consider the 'heat shield' is as strong as aluminum foil...
I guess the Smithonian Mesuem gave up the Enterprise for this experiment, but why?
It is a national treasure and they are destroying it!
Good thing you pointed that out. I'm sure I wouldn't have known that damage depends on more than kinetic energy. Ten years of engineering doesn't appear to have taught me anything.
Seriously dude, way to miss the joke.
Hey, they ARE in league with those darn commie reds!
You say "I would think". Well, if I was a responsible engineer at the time and place, I would have thought of a lot more than either you or they seem to have.
1) Aerodynamic drag at 50,000 feet is hardly "negligible". Drag is proportional to local atmospheric density times the square of the velocity. Atmospheric density at 50,000 feet is 15% that at sea level. Therefore the drag at that altitude is equal to the drag at sea level at 39% of the speed. In other words (pick a number) 500 mph at 50,000 feet causes the same drag as 195 mph at sea level.
2) Therefore, not only was the space shuttle ACcelerating, but the foam was DEcelerating - probably a LOT - but the point is, it needs to be taken into consideration.
3) The foam coating the fuel tank is HARDLY the same as that a nerf ball is made of. It is much more substantial.
4) As I understand it, the piece of foam that broke off was very likely coated with ice. I think if you got hit by a piece of ice travelling 75 mph (much less at an even higher speed), you would most certainly be injured, and so would the leading edge.
5) Prior strikes were grazing blows on the surface of the wing. We are postulating a direct hit on the leading edge of the wing, made up of very brittle carbon fiber composite.
All that said, in the end I don't blame those on the scene as much as those responsible for the crappy concept as a whole. Hopefully I would have thought of the case of a direct strike on the leading edge, and hopefully I would have woken up to danger (albeit maybe too late) when a piece of the shuttle was OBSERVED to part company while in orbit, but my true ire is reserved for whoever is responsible for the design concept as a whole. If the fuel tank was coated with crappy insulation that frequently broke off in chunks during launch, that in itself doesn't constitute a hazard. But as soon as you mount a manned space vehicle directly in the path of the debris, that is just unforgiveably negligible.
This is not a troll. I am genuinely curious and haven't seen an explanation in the stories:
How did the combined velocity of foam + shuttle hit 531 MPH? As I understand it, the foam broke off of the fuel tank and then hit the wing. The fuel tank, foam, and wing, were already travelling at 500MPH+, then the foam broke off. Certainly it would maintain some of that velocity, right? It wouldn't immediately stop in the air and allow the shuttle to hit it at full speed? My thought is that the actual speed must have been far slower -- otherwise no shuttle would have ever made it back to earth.
Please correct me if I'm mistaken.
filmcritic.com - Movie reviews on Internet time
at time of impact was at 50,000+ feet, the force of air drag on the foam would be negligible
If drag is negligible at 50k ft, then please explain to me why the shuttle broke up at 200k ft.
I think that this was the level of intuitive analysis that was done. Unfortunately, it wasn't backed up by any kind of quantitative analysis using known facts...
Where do you get this stuff? Now you're making assumptions as to what took place in meetings you never attended? Wow.
Yeah, but nothing stopped OJ from looking for the "real" killer.
All i can figure is that the chunk of foam must have hired Johnny Cochran as its lawyer....
"You want a toe? I can get you a toe by three o'clock... with nail polish."
Even after the experiment and the basic lesson in physics, they still won't say "Yeah, we are keeping our minds open to any new evidence, but right now it appears that this foam strike was the a major factor in the accident."
THERE IS NOTHING WRONG WITH SAYING "Yes, we think this is what caused the damage" If it was instead the basketball that indeed hit the shuttle, the debate about what caused the damage would be wrapping up.
There are several things wrong with saying "Yes, we think this is what caused the damage." So far, they've made a statement that is completely supported by experiment--it is probable that the foam is capable of doing damage.
Is it likely that the foam did in the Shuttle? Yes. Do we know it did? No. So they can't publicly say they think they know. What if it turns out to be a micrometeoroid, and they find evidence to support that conclusion? How about if they discover a flaw in the adhesives used to assemble the wing? What if it's a software thing--once per century, the computer will decide that the Shuttle is upside down and move to 'correct' it. They have to retract their statements, present new data, upset the powers-that-be. Administrators get raked over the coals in Senate hearings, because they 'changed their story'. Senators looking to score political points and move dollars from NASA to Disney demand to know, "why should we believe you now, since you lied to us before?"
If an airliner crashes in the United States, the NTSB will investigate, and usually keeps a very tight lid on all speculation until they can issue a final report. This is how it should be done. You don't whip off a press release as soon as you have a plausible scenario--you test everything. Investigators looking at other areas might be tempted to get sloppy if they perceive that their superiors have already 'decided' what the cause of the accident was.
Those on /. more than twenty-five years old or so will remember the incidents involving the Therac-25 radiotherapy accelerator. Early accidents were attributed to a faulty microswitch, and investigation ceased at that point. Consequently, several more people were injured or killed because nobody kept looking for the real problem--a software bug.
One more thought regarding the 500 mph basketball impact--your car is not designed for flight at many multiples of the speed of sound, or for atmospheric reentry. We're working in a realm where most laypeople should definitely not trust their intuition. (Foam sounds light...but 500 mph is pretty fast...what does it mean?) My training actually is in physics, but I'm still leery of making guesses.
~Idarubicin
...since the slipstream is stressing the wings. Any analysis of the problem needs to take into account that the leading edges are under significant stress. This is why the SSME's are throttled back during the launch, to reduce the maximum loading on the airframe.
The insulating foam for the space shuttle that broke off and possibly destroyed the shuttle was a new formula since 1997 that has been problematic since it replaced a freon based foam. Although the freon-based foam worked better, the new foam was used instead rather than getting an exemption. So, if the foam is the root cause, it appears political correctness was more of a concern than using the best material for the job, possibly costing the lives in the process. Here's an article on the subject
Vote for Pedro
The guy that made those comments isn't a rocket scientist. Just because someone works for NASA doesn't mean that they are a rocket scientist, nor that they have had any scientific training (think technicians). Some people that work there do pure and applied math. Some do physics. And some, like the administrator of NASA Ames, have a background in radiation measurement. (Check his bio, as someone posted above.) Plus, the guy is in management. Which brings me to another point. There are two kinds of engineers: the technical types (like me), and the management types. The technical types will sometimes debate the finer points of number theory, quantum physics, string theory, or fusion. The managerial types will have their eyes glaze over with that deer-in-the-headlights look when you mention any sort of equation.
I quote from the article:
"That's when it came home to me what 1/2mv2 means"
That is a very scary thing to read!!
The researchers estimate that the test will exert about 70 percent more force than necessary to shatter a composite panel, Mr. Hubbard said. "Now, whether it actually turns out that way or not, that's why we do the experiment," he said. "But the analysts are saying it looks like it'll break it."
The analysts could be high school physics students in this situation and they would even know that saying it looks like it'll break it is a complete understatement.
"Jerk store Jerry, jerk store... Jerk store!"
The shuttle was 81 seconds out when the tile hit the wing. At 70 seconds after launch, it's about 49,000 feet above sea level, so lets say at this point it was around 60-70 thousand feet up
I'm not sure about you, but I don't know too many birds that fly TEN MILES miles above sea level.
You may disagree, but to be blunt, you're wrong. -tgd
It's looking more and more like there was a management decision to accept foam impacts despite the engineers of the shuttle specifying that nothing should impact the shuttle.
Previous reports indicated NASA management argued that the impacts were OK since nothing bad happend from past impacts,and because it was "just foam". Some of the same articles stated that the engineering design docs stated no impacts were acceptable.
The challenger disaster was for sure due to managers deciding to launch against the strong advice of the engineers not to launch.
This current article's quote of the NASA Ames person (who has been in management for awhile now as someone has already pointed out) surely is suggestive of the problem. It indicates his surprise that the physics don't match his inuitive expectation. Maybe that's a root of the problem. People with some science background in a non-relevent field who move on to a management role are relying on their own intuition over that of those that are doing the actual engineering in the relevent field.
For sure if they were going to accept the impacts then they had a responsibility to put the resources into experts carefully analyzing what the outcome would be for all the possible impact area's and times. That would allow a scientifically informed decision.
Instead there was an intuitivly informed decision.
..and does it matter?
Are we talking "bubble bath", "nerf ball", or "beer cooler" here?
Which brings to mind an experiment requiring a NASA scientist, a medium-sized beer cooler and a lot of compressed air...but that's another post.
To me it is absurd that the engineers did not think of this. If it were me I would fire every one of them. "Oh it's just a piece of foam" shows complete ignorance of some basic physics. When lives are at stake, I would think people might take a little more caution. That's my two cents!
You would be wrong. You're thinking maybe the walls of the lunar landers (never exposed to anything but vaccum)? Even there the aluminum foil comparison is a bit of an exageration. The "heat shield" on the shuttle is thick ceramic tiles.
Great, so they can destroy it?
A Cessna? How much does that weigh in Volkswagon Beetles?
From the article:
The exact conditions of the actual foam strike â" with extremes of vibration and temperature and near vacuum, could not be duplicated at the test site, so the researchers have had to improvise and try to match the conditions as best they can, Mr. Hubbard said.
The upside to monitoring every inch of the shuttle with cameras is that you can detect any *visible* damage.
The downside is that you'd have to reengineer the frigging thing. Where are you going to mount the cameras? And keep them from melting? and how much will the resulting proposed solution add to the weight of the craft? How are you going to integrate the data from the cameras, are you going to get a bunch of guys to watch them intently the whole flight? and finally, is it the best solution for the weight and cost?
The camera could detect the damage, but probably isn't the most appropriate *tool* for the *job*.
I'm lame.
First off, I'm a Logic Nazi, not a Logistic Nazi. Go look up "logistics" if you don't understand why.
Now, a rail gun uses electromagnitic force (opposites repel) to motivate a small conductive mass. Because of the amount of energy available, they can accelerate this projectile to very high velocities, moreso than a standard chemical explosion could.
Also, NASA does track space debris, thousands and thousands of bits of it.
Birds take down planes, and could probably take down the shuttle. I guess they're just playing the percentage game here. And how high do birds fly? I'm sure that after the first few thousand feet, there aren't any more birds. So you've got to worry about maybe the first few seconds. This last bit is pure conjecture, so maybe a more knowledgable Logic Nazi will come along...
That 1g spec of dirt would only have to travel 632mph to have the same kinetic energy as the 1KG block travelling 20mph.
If you're looking for some of the images, they're inside a presentation right here.
The fact is, even if the shuttle were accelerating upward at 4 G's (a sustained acceleration of 4G is huge), and the foam accelerating downward at 1 G, for a total acceleration of the foam relative to the shuttle of 5 G's, then in falling a distance of, say, 200 feet along the shuttle the thing would only be moving at sqrt(2*5*32*200) = 253 ft/s = 172 MPH. And 200 feet is an overestimate. From looking at the video, it's easily shown that the thing was really moving closer to 500 MPH. The difference of 328 MPH must have been caused by some other force, and the only other possible force is wind resistance.
You can't argue with fact.
I put foam in my pants AND I run fast
lick the cancle button (at least thats what our Chinese QA says)
These tests were conducted in Houston, They forgot the simple truth that everything is bigger in Texas. So, the great-biggest-on-Gods-green-earth-Texas-style foram used in test was probably much too large and tough compared to the wimpy-geriatric-I-am-here-because-I-retired Florida foam. Again, NASA engineers do not get the units right. Sigh. :)
my two cents
Iowa
"He who laughs last, didn't get the joke."-Cap
I think we need to decimate NASA. Since no one at the agency is willing to accept any responsibility for this disaster and since we are never going to get any straight answers out of NASA we need to just assume that the incompetence is collectively distributed and fire one employee in ten, selected at random across all pay grades and all NASA centers.
The fired employees will not be allowed to ever work for the government again, or to work for any government contractor or to work for any state, municipal or local government that is receiving federal funding or to collect any pension or benefits from the federal government. While this might sound harsh the fact remains that they are alive, the Columbia astronauts are dead.
cheap labor conservatives - they want to keep you hungry enough to be thankful for minimum wage.
Yes, the foam needs to be fixed, but it wasn't like the O-Ring problem in the Challenger accident when the weather conditions caused a catastrophic failure of the seal. Rather this was a catastrophe that unfolded over many years and culminated when a NASA spokesman told reporters that the falling foam was not a problem.
Just a quibble -- so far it looks like this accident has very much in common with Challenger. Not only was the Challenger SRB design off the mark, but there were complaints from engineering after O-rings were partially damaged in earlier flights, most notably Boisjoly of Morton Thiokol, the SRB contractor. Worst of all, NASA basically strongarmed a waiver of existing temperature restrictions, launching at about 20ÂF below the design spec.
Thus the catastrophic failure of the seal was ultimately caused by defective NASA decisionmaking (the foundation having being laid by the seal design). I'm sure whether this was a dumb error or a "smart" error, but do think management will be the ultimate party responsible.
So we see possible common elements of defective design and failure to react to early problems.
...Empire State Building tourists who throw them do.
Charles Hessin, President NPA
National Penny Association
... could be possible terorist weapons :)
Well, one of my goals in college was to break the speed of sound with a nerf ball. We hit mach 1.3 with a modified potato gun and the little "ballistic balls". I can assure you, at those speeds a nerf ball is incredibly destructive. I can't even imagine what it would have done to a spacecraft's wing.
If you're wondering how we measured the speed, we used two metal foil strips with current running through them, such that it would generate a square wave when the foils were broken. We captured the signal with a computer soundcard, and just counted the samples to measure the period of the wave.
There's something that no one has mentioned here: These first tests were static.
Although, it will probably not be necessary, a more realistic test would include flexing and vibrating the wing during the test.
And before anyone says, "what difference could would that make," remember that the NASA engineers originally said the foam wasn't capable of any damage in the first place.
The Columbia had three big, friggin' engines running and the entire vehicle was under all sorts of dynamic stress. These tests ignore those factors.
Just an observation...
--Richard
PS: The new OmniWeb is great.
Whenever a plane "hits paydirt" as a result of hitting something else first (excepting other planes, of course), it seems the universal constant is a jet engine's intake manifold. A flock of birds, a weather balloon, a lost Australian Shepherd asking for directions, they all get sucked into the engine and wind up tearing it apart from the inside. IANA air traffic controller, but in my experience, that's the only reason a plane goes down as a result of an unexpected collision (excepting the ground of course).
The shuttle has no jet engines, and there's not really a way to damage the rockets that propel the vehicle except creating a breach of some kind.
With that in mind, I'd imagine the damage likelihood would be extremely low (famous last words?) if a bird hit the shuttle during liftoff. Beyond the already high unlikelihood of an actual collision (NASA has played the percentage game quite a few times now), their small bodies are padded by a relatively huge volume of feathers, which would absorb most of the impact. I won't stray far enough offtopic to divulge details, but four ingredients: younger days, an old Victorian house with an open-air attic (or whatever construction guys would call that), pigeons pooping all over the place, and a bb gun. That thing could embed small metal spheres half an inch into hardwood stairs (won't tell you who still doesn't know about that, either), but when pigeon hunting, if it wasn't a head- or neck-shot, the bb would just bounce off, sometimes not even scaring away the damn pigeon. Now don't call the ASPCA, because that would be too far offtopic.
So anyway, to bring down the shuttle, the bird would have to try to impale the craft with its beak, and that's only possible if the bird is looking down (it it a faux pas to say FTSOA that the launch is vertical?). Now, I won't pretend to know that a bird definitely could/couldn't get out of the path of a large object moving at mach three, but I think it's fair to assume that most birds would see it in time to at least attempt flight (sorry, bad pun), and therefore be facing away from the shuttle, enabling the rocketing craft to hit the soft part of the bird first. So, of the multitudes of birds that hit the shuttle during each liftoff, only an infinitesimal percentage would collide beak-first. I doubt birds are of much concern to the shuttle crew.
AFA the rail gun analogy, it's actually like electromagnetic charges that repel, not opposites, which attract. Other than that, your statement is very true.
I probably shouldn't mention these small details, but without the existence of small details, this entire thread would likewise not exist, right?
All right, I just couldn't resist the correction. So I qualify.
- zedmelon
Mom says my
Now I know.
Thanks Slashdot.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
Actually the decision was indeed based largely on historical events. There had been a least a couple other instances of foam coming off and striking the shuttle. In these cases the damage was minimal. As I recall there was also some simulation work that was used in the decision.
"It takes considerable knowledge just to realize the extent of your own ignorance." - Thomas Sowell
Almost right.
"Seems to be that this type of bad decision making is what needs to be addressed at NASA. Yes, the foam needs to be fixed, but it wasn't like the O-Ring problem in the Challenger accident ".
No. Like many science institutes today, NASA is run by bureaucrats who focus on politics and accounting. Columbia died for _EXACTLY_ the same reason as Challenger: the decision-making was _NOT_ done by the engineers and scientists (aside: go find out what happened to the engineers who warned against launching Challenger).
Unless NASA returns to "the good ole days", when the engineers were in charge, or it invents a new management paradigm in which real authority rests with the engineers "at the coal face", ships and people will continue to die.
Perhaps NASA should adopt the Japanese car-maker's paradigm - where a single production worker can stop the entire line if they see a problem.
In reality the way we do institutional science everywhere desperately needs an overhaul - but bad decisions at most reseach institutes only waste money - not lives.
I want to see photos of the tank with the missing foam please. Until then I will hardly believe this is related to the foam falling off....
thank you and the other post for pointing out that challenger accident was not a surprise to some people within NASA either.
You make the point I was trying to make, bad management tries to shift responsiblity down to committees of engineers. Seems more like people are trying to cover themselves rather than let reason prevail.
I would have rather have had a single person stand up and say "I decided that there was not enough risk to justify further investigation of the foam problem" rather than have several layers of management pointing fingers at groups of engineers at a subcontractor and saying that they didn't think there was a problem and just leaving it at that. the physics, the material science, even common sense all say that when an aircraft get's hit with something going very fast, then there could be damage. So, given that foam had fallen off before and hit the shuttle, and that they had video of it hitting the shuttle Columbia could they not turn the Military spy cameras onto the shuttle? Are we missing something here?
Maybe it is too harsh to think that any reasonable decision making would have saved those lives, but I have to believe that reason should have led to a greater effort at many of points along the way.
Whups. I got my rather limited set of physics equations a bit scrambled.
:-D
e nergy/u5l1c.html :-D )
let's see: KE = 1/2 m v^2
So, the 1/2 does factor in, but the v^2 is still the biggy. So, errr, I was half right?
source: http://www.glenbrook.k12.il.us/gbssci/phys/Class/
(Thanks goodness for Google and basic high school classes online.
--- I wish I could hear the soundtrack to my life. That way I'd know when to duck.
What I can't possibly fathom is:
Why the $%I($$* didn't they test for this AGES AGO!?!
They've said for years they knew about this, and how can the entire engineering staff of NASA MISS something like this?
It's like building a new car, and not testing for crash resistance!