Wing Seals Blamed in Columbia's Demise

MoonFacedAssassin writes "MSNBC has this article stating that a 'seal from Columbia's left wing was apparently the mystery object that floated away in orbit, and it was almost certainly struck by something - like a chunk of foam - before it came off, accident investigators said Tuesday.' The article also quoted Navy Rear Admiral Stephen Turcotte, a CAIB member, as having a confidence level 'up there near the 70s and 80s percent' about the T-seal."

Comments

Amazing...

[Anonymous Coward]

These shuttle disasters keep proving how important seals are in our lives, no matter how mundane or simple they appear to be.

The widespread practice of clubbing them, especially the baby ones, has got to stop.

Re:Amazing...

[GigsVT]

Don't worry, the recently passed RAVE act will put an end to all clubbing.

A flying seal!?

[91degrees]

What was it doing up there? Shouldn't it be in the arctic headbutting clubs or something like that?

I read...

[crevette]

... Winged Seals responsible for Columbia's desmise.

You know, with all the flying pigs we've seen lately...

Re:I read...

[ackthpt]

... Winged Seals responsible for Columbia's desmise.

You know, with all the flying pigs we've seen lately...

and all the cow manure out of Washington lately, but that's beside the point. O-Rings, now T-Seals. There's an alphabetic trend here. I wonder if it was C-Foam.

Ever get the idea these things are built like models?

"Insert Seal (T) in Wing Assembly (A)"

Confidence Level

[therecaller]

So, if it's not 100%, they just give it another arbitrary number to feed to the media?

Re:Confidence Level

[GuyMannDude]

So, if it's not 100%, they just give it another arbitrary number to feed to the media?

Yeah, that was my reaction on reading the summary as well (god forbid I read the article). Just for once I'd love to see some members of the media really hold NASA's feet to the fire and ask some really tough questions in the press conference. Like "How did you come at that confidence value?" And if the NASA spokesperson hims and haws and doesn't give a solid reason, then the reporter ought to point out that if there is so much uncertainty in the accuracy of the confidence, maybe the answer itself isn't really 70-80% accurate.

The problem is that the media has settled in to a nice, comfortable role of transcribing press conferences mindlessly and reporting them verbatim to an equally mindless public. Where the hell has investigative reporting gone? Surely the cause of the disaster is beyond the ability of most news outlets to investigate for themselves but they should certainly be able to ask some tough questions and pass NASA's explanation through a sanity check.

I realize I'm going a bit off topic here, but I'm really getting sick of the crap in the media. The 'authorities' are just throwing out random numbers knowing that no one is going to bother to question them. The sad thing is that once those numbers are 'out there', they become accepted simply due to their familiarity.

GMD

What a suprise

[(54)T-Dub]

From the begining they said that at least two pieces of debris hit the wing during launch. It seemed pretty obvious to me that this caused the problem. I guess they didn't want to admit that they had been wrong when they gave the go ahead to re-enter.

Re:What a suprise

[Wyatt Earp]

"I guess they didn't want to admit that they had been wrong when they gave the go ahead to re-enter."

There was no other option than to re-enter.

On Columbia's mission there was no abort to ISS. Once it was up there, the only way for those astronauts to come home was to re-enter.

Re:What a suprise

[Exedore]

Well, I don't think that's exactly being fair to NASA. The foam hitting the wing on liftoff was a leading theory all along. What would you have them do? Declare from day one that the foam incident caused the disaster and then lose another shuttle down the road because they were wrong? No, I think the methodic approach is best in the long wrong.

Another point: regardless of what the exact cause is, something obviously went wrong and NASA would have to own up to it no matter what it is. So I don't think the pace of the investigation had anything to do with an attempt to dodge culpability.

Re:What a suprise

[Fastolfe]

Based on the information they had at the time, the risk that there would be catastrophic damage from the foam hitting the wing was not significant.

If you are 99% positive about something 100 times, you will be wrong once. Sometimes margins of error and lack of data lead you to an incorrect conclusion.

They could not have foreseen the damage and based on their extensive knowledge of the orbiter and the nature of the foam and impact, determined that any damage was unlikely to pose a re-entry risk.

This may seen "obvious" to you and all of the other armchair NASA administrators out there, but they had to investigate to be sure, and to understand precisely what happened and how it happened so that when similar situations come up in the future, they can make a more educated analysis of what form of damage is likely and what that damage is capable of. It would be just as irresponsible for them to claim this was the problem and close the book on the case in the first week.

Please give the guys at NASA a little more credit.

Re:What a suprise

[Fastolfe]

And you know this how?

Because they said it? Repeatedly? Because this is what all of the published information about the conversations, e-mails that went between researchers, managers, etc.? The event and review have undergone a tremendous amount of scrutiny, and most of that was as transparent as I've ever seen.

The leading edges and the protective tiles were never designed for ANY impact.

So? I have a picture frame that wasn't intended to withstand an impact. If I throw a ball at it, though, I can pretty accurately estimate whether or not that frame will be damaged based on the nature of the ball, the speed I throw it, and where the impact occurs.

Do you want me to repeat that.

If it makes you feel better..

he leading edge Carbon-Carbon structures and the protective tiles were never designed for any impact.

Do you feel better?

under conditions it was not designed for and which they did not understand.

I don't guess you're in charge of many missions to space, so I'll try to explain this in layman's terms. Operating an orbiting spacecraft is a high-risk endeavor. You very much do take into account potential unexpected hazards when you design and build one of these crafts. You take certain economical measures to ensure that things like micrometeroid impacts don't threaten the life of your crew, and try to plan contingencies to handle unexpected events. Just because someone didn't "rate" the craft's hull for a certain type of impact doesn't mean impacts of that type were completely ignored or unplanned for, or that the craft will be unable to withstand them.

Again, go look at the immense volume of information published during this investigation. This wasn't a cursory ho-hum "it doesn't matter" check, nor was it a "holy crap, it wasn't designed for this, they're going to die, but let's not tell anyone" type of thing. The experts there (of which you are not one) examined the data at their disposal (which you do not possess) and consulted their own education and experience with the program (which you do not have) and made a determination (which you are not qualified to do) that the risk to the orbiter was low. This is proving to be incorrect. That doesn't mean they "fucked up". They had no way of knowing any better. Again, if you're 99% right 100 times, you'll be wrong once. It happens. Deal with it.

If you're going to ignore the advice of the experts, just because that advice very infrequently ends up being wrong, you are going to end up wrong far more often than not, much to the detriment of the space program and the lives of those depending on you.

Especially when equipment is experiencing conditions it was never designed for.

If you can design a spacecraft that's perfectly safe, and designed to withstand any and all forms of abuse and unexpected events that the existing orbiter could potentially experience, and do that at a cost less than 100 times what the existing orbiter costs, you will be rich.

Again, sending people into orbit is a highly risky activity. You have to spend money to be prepared for certain types of events, but when the likelyhood of those events is low and the cost to mitigate them is high, you have to make a decision and frequently a compromise. If you don't understand this, or have issues with it, feel free to make them known, but I applaud our astronauts for being willing to take these risks on our behalf, and I applaud NASA for making the achievents they do with the funding they have. I wouldn't have it any other way.

continued to flaunt their disregard for basic engineering principles.

Whoa there, this is a pretty loaded statement. In what ways does NASA continue to "flaunt their disregard for basic engineering principles"? Care to give us some examples? Or are you just throwing out unsubstantiated, emotional statements because you're pissed off at something?

Do we continue to have Slashdot readers that think they can do a better job than the guys with the PhD's and decades of experience? Maybe you should start up your own space exploration company.

Re:What a suprise

[RatBastard]

There was not enough fuel on the Shuttle to match orbits with the ISS. It's not just a difference in altitude, but in direction and velocity. They simply didn't have the means to get there. And it would not mattered if they did. There was no docking collar on the shuttle. And an emergency rescue launch was laso out of the question. It takes a minimum of 3 months to prep a shuttle for launch and there were no shuttles anywhere near launch status.

The bottom line with teh shuttle program is that if something goes wrong the astronaughts are screwed. But that has been true since the days of Project Mercury.

Re:What a suprise

[Soft]

Well, there was no contingency plan. The Soyuz on the ISS has enough fuel for a complete deorbital burn; would that be enough to drop to LEO and the shuttle, and then reascend?

No. The ISS is in LEO (400km altitude; neither shuttle nor Soyuz can get much higher), it's a question of orbital inclination, which takes as much fuel to change as it took to get the spacecraft in orbit in the first place. (Well, roughly; I had calculated that 120-160tonnes were needed, the external tank at launch holds 2000, and the Soyuz less than1...)

But I imagine if you abandon the idea of a deorbital burn on the shuttle and instead use the fuel to get to a higher orbit

Not even close, I'm afraid.

I don't know if you could squeeze all seven astronauts into a three person capsule either.

Not for a return to Earth (the seats are form-fitting and the landing quite hard), otherwise possibly, but the more people aboard, the more fuel is required to get anywhere...

Maybe multiple trips would have been required. Can the shuttle and the Soyuz even dock?

No. And they don't use the same docking ports on the ISS either.

That might have required EVA's...in any event, I think that with all of those resources in orbit, something could have been worked out if NASA had committed to a solution.

No. The best bet, provided that the danger were known at the beginning of Columbia's mission, was to conserve power so as to last maybe an extra week or two in orbit, and rush Atlantis through launch preparations, bypassing a number of safety regulations to have it ready in less than a month. And only because it happend to be already sitting on the pad.

Sorry to sound rude like that, but I hear this kind of misconceptions so often...

This may all seem pointless, but it's not: at some point, we will encounter this situation again in some form. "Orbit to ISS" is not part of the any shuttle mission profile; perhaps it should be from now on.

It is said to be in the cards. Not that it would help (the ISS can't hold that many people for long), but no mission was planned elsewhere except for the last Hubble repair before its planned end of life, and all interesting places to go are out of the shuttle's reach anyway.

Re:What a suprise

[Soft]

Let me try to explain better. There's a usual range of orbits the shuttles get into, to service satellites, and such, right? The ISS is not in that typical range, hence the short-term survival problem.

Now I see what you meant. But there is something you missed: the orbits which can be reached by the shuttle are not at all the same as those orbits which it can reach after being launched into a different orbit.

Imagine you are making a trip with a car, and a bike inside the car. Assume that no gas stations are available, and that you want to consume the car's whole tank and then ride around with the bike. You can go a few hundred km with the car, say either from Paris to Geneva or from Paris to Brussels. But once you have arrived in Brussels, you can't change your mind and use the bike to get back to Geneva.

It's the same with the shuttle: it can go to the ISS, but you have to decide on it before launch. Afterwards, your fuel is gone, it's too late.

So the problem with your idea is that you would have to park and maintain boosters or fuel tanks at every possible orbit that the shuttle might want to reach, which makes a lot of them.

Basically a really-big satellite full of solid rocket fuel/oxidizer. I assume it would have to be launched by a shuttle being that big, so it would be volume limited to the size of the shuttle's cargo bay. Of course, I'm ignorant of the relevant energy densities/energy necessary for orbital changes.

A shuttle can launch 20-30tonnes of payload to low Earth orbit depending on the orbital inclination (the higher the more difficult except below the latitude of Cape Canaveral, which is impossible when launching from there). Last winter's event would have required 120-160tonnes of fuel to get to the ISS--with a moderate-efficiency engine such as the OMS or a kerosene-oxygen one; solid motors are not as good. But you could station a full tank every few degrees and use several of them, each getting you to the next one.

Expensive but not impossible--that could be interesting once we develop a space-based infrastructure, with materials and fuel coming from nearby asteroids or maybe the Moon or even Mars.

And, of course, this doesn't solve the problem of keeping everybody alive more than a few days at the ISS.

That's the Bush Administration for you...

[Interrobang]

They always use the media to blame everything on the left wing!!

/me ducks and exeunt chortling

A chunk of foam?!

[gpinzone]

They really gotta start building these shuttles a lot stronger. I mean, even the wimpiest kid doesn't flinch from getting hit in the head with a nerf ball.

Re:A chunk of foam?!

[MentlFlos]

Yes, but make that foam the size of a basketball, soak it in water and freeze it solid. Then drop it many stories onto said kid and see how the flinch goes.

Re:A chunk of foam?!

[athakur999]

The foam is quite a bit more rigid than nerf ball material :) It's more like hard foam some bicycle helmets and knee pads have in them... I used to intern at the place that makes the external tanks and had a chunk of the foam at my desk.

Re:A chunk of foam?!

[AKnightCowboy]

I used to intern at the place that makes the external tanks and had a chunk of the foam at my desk.

See? That shit is falling off left and right. Maybe they should find some better material.

next problem

[ih8apple]

First it was the O-Ring in 1985
Then it was the T-Seal in 2003


Logically, the next problem will be with the Y-Tube in 2011.
Science and Logic Prevail!

Re:next problem

[ih8apple]

...except for the fact that I can't do Math....
that should be 2021

Re:next problem

[John Harrison]

I realize your post was made in jest, but there are some serious differences that this brings up.

Remember how quickly and how harshly politicians jump on Thiokol after Challenger? They wanted to move all shuttle work to a different company. Now that some of the big boys might be at fault with Columbia nobody is up in arms. Why do you think that is?

Re:next problem

[FTL]

> Remember how quickly and how harshly politicians jump on Thiokol after Challenger? They wanted to move all shuttle work to a different company. Now that some of the big boys might be at fault with Columbia nobody is up in arms. Why do you think that is?

Challenger was a disaster waiting to happen. There were engineers at Thiokol who knew the shuttle was probably going to blow up (though they thought it would happen before it cleared the tower). There was clear blame in Challenger's case: management wouldn't listen.

Contrast with Columbia. It's been two months and we've finally figured out the sequence of what happened, but to date we still haven't figured out why it happened. We don't know yet whom to blame: the manufacturers of the external tank, the manufacturers of the heat shield, the original designers of the shuttle, the people who drew up mission contingency rules, the managers who signed off on some key decisions. Only once we know why Columbia was lost can we start thinking about blame.

I commend the media and the politicians for not scape-goating someone for this. Instead they've let the investigators methodically get to the bottom of things. It is an unexpected level of maturity I respect.

Re:next problem

[Ryan Amos]

We Americans are too quick to assign blame. Hell, we didn't even know anything was wrong, so how can it be anyone's fault? Yes, some horrible consequences can result even if everyone involves carries the very noblest intentions and has no real hand in the matter. So the most we can really do from them is learn from them so they don't happen again. There is nowhere to blame here, which seems to be scaring some people. Get over it, it was an accident. More people die in car accidents in a day, and probably suffer a lot more than these people, whose bodies were incinerated in about .5 seconds anyway, but they were already dead because the rapid depressurization of the cabin caused their blood to look like a can of Coke. Death really doesn't come more instant and painless than that. Blame nobody and look to the future.

And this is going to effect NASA how?

[confused philosopher]

There aren't going to be any great changes from this finding. We are still going to use the Shuttles. Only thing now is that we are going to "cross our legs and hope to fly," in the words of a great Canadian Prime Minister spoof.

more info

[pjgeer]

New Scientist also has the latest.

You mean there are seals that live on...

[kahei]

...oh, wait, I just realized that every other bored person on the entire face of the planet must be making the same joke.

Long Live the Shuttle ... now lets move on.

[Jedi Holocron]

The Shuttle is a wonderful experimental spacecraft. Let's all keep that in mind. Designed in the 1960's, built in the 1970's, finally flown in the 1980's on 20 year old technology. The world's first partially reusable launch vehicle. Kewl!

Okay, let's move on. Oh wait, we didn't. We floundered with National Space Plane projects. The X-33 was sacked. The Delta Skipper was sacked.

Hey, let's continue to rely soley on an outdated experimental concept vehicle can continue to stick roman candles up our kiesters as a way to get into "space". We'll live with the limited altitude (no micrometeorioid protection), limted power, limited duration, etc... etc...

Okay, sorry for the slight rant there. The shuttle rocked but it is time to move on. Why haven't we? If NASA had a budget that was maybe, at the least, equal to the increase in defense spending for 2003 we might be able to do this.

We are not. Maybe we just haven't found the reason to really want to go to space. I dunno. it is frustrating.

My graditude to everyone that has ever dared to travel to space. My thanks to those that have lost their lives in the endeavour.

brilliant way to disagree...

[Goose Bump]

Physicist James Hallock, another board member, said he does not believe a missing seal alone could have created a big enough hole for the kind of heat damage experienced by Columbia. As the plumes of hot gas entered the long, narrow gap, it probably chipped or broke away at the adjoining wing panels and created an even bigger breach -- enough to lead to the ship's destruction, he said.

Isn't this kind of like saying the bullet isn't what killed him, it was the hole it left behind?

Re:brilliant way to disagree...

[WegianWarrior]

He is an expert. He is expected to say this sort of things, in fact, it is what he is paid for. And in some ways, it make a lot of sence; if the hole / gash hadn't opened up further, the ingress of hot gas may not have caused enought damage to the structure to cause a failure.

To take another example I know more intimatly; We (the RNoAF) lost a F-16AM during Operation Enduring Freedom this winter, when both main landing gear tensionstuts collaped on landing. Now, at the surface, we lost it because the struts broke. Dvelving deeper into it however, showed us that the struts broke because the jetjockey slammed a fully loaded, newly refuled (from a tanker aircraft) into the runway with a sinkspeed three times the limit.

Sometimes what you think causes the failuer is but the start in the chain of events, sometimes it is the last bit of it.

Re:Safety Record

[taschuk]

A catastrophic failure rate of ~1% is not comparable to any other form of travel that I am aware of. Space travel is not a safe occupation. That being said, it is an important task and should be continued. I also hope we don't see any more fatalities, but this seems an unreasonable expectation in a young field.

transfer of kinetic energy

[lazira]

It had to be the result of some blunt-force trauma, the transfer of kinetic energy, somehow

I gotta remember that term. Like: "how about I transfer you some kinetic energy" or "Ouch! That transfer of kinetic energy was uncalled-for."

Don't you mean...

[BlackGriffen]

The U-Vent?

Then they can finally move on to the X-Window, and finally the Y-Zipper!

BlackGriffen

When I read this title

[dlakelan]

The title of the story made me think:

Seals? With wings?

Time to take that bong away from the aerospace engineers.

Re:obvious?

[Mononoke]

Once again, something even CNN knew BEFORE RE-ENTRY! I want to be a NASA expert and get paid to twiddle my thumbs.

Yes, but then you'll be the one called upon to give the astronauts their final choices:

1. Risk dying upon reentry if the calculated damage figures are correct.
2. Meet the certain fate of freezing to death staying out in space while committees decide if they can bring you home.

I don't want any warning before I die. My affairs are in order. So were the affairs of the astronauts.

I know that a shuttle is different in many ways...

[WegianWarrior]

...from a fighter aircraft, but;

"he seals are made of reinforced carbon composite and fit between pairs of panels made of the same material that are designed to withstand temperatures of up to 3,000 degrees during re-entry. These seals and panels wrap around the leading edge of each wing." sure sounds like a badly thought out design to my ears.

At mach 2+, the airpreasure is high enought to rip an aircrafts structure apart - thus we make sure that no edges stick out of the airframe, and that no holes excist or can appear in such things as the leading edges of the wings, stabs or tail. At the speeds the shuttle has on reentry, this is even more important - even if you don't factor in the heatpulse. A design which, if it breaks, opens a gash into the interior structure is thus a flawed design - even if the designer didn't think it would ever fail! And remember fellow /.ers, NASA did more or less the same error when it came to the O-rings in the solid rocket boosters; the design was flawed from the start, but they choose to belive it wouldn't fail.

As far as I recall, the shuttle does not have leading egde flaps. Thus it shouldn't be a reason for a 'split' design like the article describes, a solid leading edge panel made of reinforced carbon should be both possible and perhapes even less expencive. It is certainly among the things NASA should consider to lessen the possibility of another disaster. Oh, and make sure the foam sticks to the tank as well, or at least find a better way to test it for flaws.

Re:Safety Record

[Waffle Iron]

Actually, it depends on how you measure it. If you go on a 10-day shuttle mission, you orbits traverse somewhere around 6.4 million miles. Driving a car that far would certainly carry a greater than 1% risk of a fatality.

But you have to ask: is it worth taking on the risk of traveling around the earth 160 times just so that you can tend to a zero-g ant farm?

I agree with comments about X-33. Good investment

[zymano]

Would also create jobs! The x-33 is needed or something like a inexpenive hybrid rocket engine(rubber/nox or lox)with a new improved shuttle on the top.

Why wasn't Nasa demanding the government replace these flying Edsels' ? They didn't and there's your catastrophe.

Time to push for a new future nasa. Either go with more expensive x-33 or something more affordable. Just do it.

seals considered harmful

[wfmcwalter]

I remember reading a thing about Adm. Hyman Rickover, the father of the US nuclear submarine program. He was considering the means by which motive power would be extracted from the nuclear reactors. The scheme had turbine blades inside the reactor vessel, turning a shaft that (eventually) turned the boat's screws. This mean the shaft had to pass through the wall of the reactor vessel. He was worried that the seals around this opening wouldn't be perfectly reliable, and naturally if they ever failed this would allow radioactive fluid into the boat's compartments, irradiating the crew. The seal manufacturers assured him they could make a seal that was perfect, that would withstand all that could be thrown at it. Rickover wasn't sure, wondering if a magnetic interlock (where the reactor vessel is intact, and magnets on either side cause one shaft to move its counterpart).

Rickover took the seal guys aside, and asked them - if your son was on this boat, would you still want seals, or would you opt for the magnetic method? The seal guys thought for a while, and sheepishly replied that they'd go with the magnets. To this day, all US naval reactors have magnetic interlocks, not seals.

Fact is - seals are hard. Hard to make, hard to maintain, and hard to check. They're almost always the first thing to fail, and rarely gracefully.

So, rather than the next gen spaceplane being some slicko streamline hitech composite fibre whatnot, it should be a windowless monocoque made from thick polymerised concrete. The astronauts will need a stihlsaw to go EVA, but then a concrete spaceship needs no maintainance, so they won't have to.

Re:seals considered harmful

[seanmeister]

Where did you read that?? Last time I was in a naval reactor plant (1991, USS Theodore Roosevelt), the reactors heated water that was then circulated through a steam generator which created steam that was then carried outside of the reactor compartment to (among other things) turn a steam turbine that turned a main engine that moved the ship. That's pretty much how naval reactors work.

Re:seals considered harmful

[colonwq]

A really amazing story. The last time I was on a nuclar boat was in '94. The reactor was in the reactor compartment. It made steam that left the RC in big pipe and turned the tubins in the engin room.
The shaft going out the back of the boat did not use a magnetic seal of any kind but use a mechnical seal.

Rickover was nothing but consertive in a lot of the designs.

Maybe you should look at a Jane's Fighting Ships instead of a Jane's Comic Book. :wq

In poor taste...

[Yoda2]

...Then the mechanic said, "Looks like you blew a seal." "No, no", the Eskimo replied, "that's just mayonnaise!"

Support for Space

[JASP2]

Yo... latest polls show that 86% of Amercans feel the human risk is worth continuting Space exploration. That's pretty cool. I wonder why Politicians are so scared of approving NASA's budget ?

THe problem with the budget is not so much the small ammount they get, but the fact that the budget/mission changes every 2 years due to new officials in the house and senate and oval office. We need politicians to lock in a 15 year plan and write in riders to ensure the budget can't be changed. Then Nasa can focus on a long-term mission without worrying about next years budget cuts.

just my two-pence... and I work at the University of Colorado's Aerospace Department.

Re:Safety Record

[NoahsMyBro]

Jeezus!?!?!?!? Really?

I'd pay any amount I could manage to fly on one! I'd sell off prized possessions, lose the car and walk/bike/public transit to work, go without sex (Oh wait, I'm married, that would be redundant), sever internet access, etc.... if it allowed me to ride the shuttle into space.

I think that would be the most fascinating thing I could ever do, and I simply can't fathom not wanting to go.

Of course, while I still think the shuttle is a pretty neat vehicle, I'd also be perfectly willing to go on any other vehicle that would send me into space.

Coming back safely would be nice too, but given the current state of the technology I'd accept the inherent risks.

Re:I know that a shuttle is different in many ways

[lindsayt]

This is almost exactly the same point that Richard Feynman made in regard to the first shuttle accident: they calculate failure statistics wrong and don't properly reinforce to guarantee against disaster. I believe his example went something like this:

If a suspension bridge is expected to handle 40,000 pounds of traffic on a daily basis without failing, but small cracks begin to appear after a month of usage at that weight, the bridge has failed. It is architecturally flawed, regardless of the fact that the bridge has not collapsed. If an O-ring is 1 inch thick and cracks 0.25 inches thick routinely appear in said O-ring, there is not a 75% margin of error; the O-ring has failed. A disaster has not occured, but the structural integrity has been compromised, even if it is well below the point of a catastrophic failure.

His point was that NASA had virtually ignored all non-catastrophic failures, instead seeing how far they were from being catastrophic and calling that difference the margin of error. The problem is, the design had failed, since those non-catastrophic failures were not supposed to have happened. Hence, depending upon a device which has already shown a tendency for non-catastrophic failures is no margin of error at all.

I'm probably doing injustice to his argument since he was a genius and I'm merely a Systems Administrator, but I think it's relevant.

4 Km/s... yeh it floated away

[Anonymous Coward]

4 Km/s... yeh it floated away

The object "floating" away from the space shuttle was moving at 4 Km/s. That indicates it absorbed momentum from a meteorite. The shuttle is susceptible to meteorites from 1-10 cm. Foam is being blamed because we can control the foam. The real story is that the 1-10cm meteorites are a risk we cannot control. Unfortunately, we will never be told what the probability of a meteorite hit will be.

The same way every statistic is created at NASA...

[devphil]

...pulled out of the management's ass.

After Richard Feynman was asked to investigate the Challenger accident, he wrote up his experiences. They're published as the second half of his second autobiography.

He was stupified by the amount of fudge-factoring that went on at NASA. The MTBF for a component would be listed at 300 flight hours, and when he asked how they arrived at such a nice round figure, managers would retroactively come up with a listing where each sub-component had MTBFs listed to decimal places, 34.8712 hours, 29.1109 hours, ... and they all conveniently added up to exactly 300 hours.

Engineers were going nuts, but managers kept overriding the decisions. It was a fantastic "it looks nice on paper, therefore it works this way in real life, and fuck the laws of physics" mindset.

Why did it stay on during launch

[HermanZA]

and come off in space? There is a lot of shear forces and vibration during launch and almost nothing of that in space, so why did it come off when it did?

Upside Down?

[pz]

There's probably a really good reason, but from a naive viewpoint, the proximal cause for any chunks of foam coming off the main fuel tank being able to damage the shuttle is that during primary burn, the shuttle is slung below the tank. If the vehicle were lifted to orbit in shuttle-above-tank configuration (rotated 180 degrees along the longitudinal axis from the standard configuration), the Columbia accident might not have happened.

Anyone know why the current method (shuttle-below-tank) is used?

Re:Upside Down?

[ashitaka]

Communications. If the shuttle is on top the tank would block transmissions to and from the shuttle.

Did anyone read that

[Loosewire]

And think "Winged seals - i didnt know there were any species of flying seals" ;-)

Re:The same way every statistic is created at NASA

[Dastardly]

The MTBF for a component would be listed at 300 flight hours, and when he asked how they arrived at such a nice round figure, managers would retroactively come up with a listing where each sub-component had MTBFs listed to decimal places, 34.8712 hours, 29.1109 hours, ... and they all conveniently added up to exactly 300 hours.

Is this as bad as looks with lower MTBF numbers adding up to a higher MTBF number?

Dastardly

BZZZT WRONG!

[ashitaka]

Shoulda checked before posting, although that was my recollection.

The shuttle turns over so the crew can see the horizon and have a visual frame of reference if they needed to take over manual control without instrumentation in case of an abort. Sitting on top of the external tank they wouldn't know where they were.

Number of expected failures

[sjbe]

I'm going from memory here but there are about 20 mission critical parts on the shuttle. If any one of these fails, there is no backup and a disaster will occur. Now remember, the shuttle is designed to a cost and the parts have something like 0.9999 reliability. Designing in more reliability would mean more cost so that wasn't going to happen. That means there is a roughly a 2% chance of catastrophic failure on any given mission. There have been 113 mission so the number of expected failures we should see is 2.26 (=(1-0.9999)* 113)).

This doesn't mean any given mission will fail, but we can be quite sure that we will lose one regularly no matter how careful NASA is. Thus because the shuttle was designed for a given level of reliability, we should expect to lose one roughly every 50 flights. Challenger was mission STS-51. Losing the Columbia should not surprise anyone. We should have expected to lose a shuttle around this time. Tragic but not surprising.

Re:I know that a shuttle is different in many ways

[squid_wrangler]

"A design which, if it breaks, opens a gash into the interior structure is thus a flawed design"

"As far as I recall, the shuttle does not have leading egde flaps. Thus it shouldn't be a reason for a 'split' design like the article describes, a solid leading edge panel made of reinforced carbon should be both possible and perhapes even less expensive"

You sound uninformed and are speculating without even attempting to research the subject. The RCC (Reinforced Carbon-Carbon) panels have gaps between them for a reason. The panels are mounted on floating joints to reduce the loads placed on them due to wing deflections. This also helps reduce the effects of mismatched thermal expansion coefficients between the aluminum wing structure and the carbon composite material they are made of. You can read more about the RCC panels and their attachment to the wing structure at:

http://science.ksc.nasa.gov/shuttle/technology/sts -newsref/sts_sys.html#sts-rcc

Your comment that a design that causes a breach to the interior structure in case of failure is a flawed one doesn't make too much sense either. The TPS (Thermal Protection System) design is there specifically to protect the orbiter structures that cannot withstand the heat of reentry. Therefore, by design, if the TPS was not there, the structure would be breached. You should look for flaws in the design based on a lack of anticipation of possible external damage modes and not in that it was a very critical system whose loss results in an overall failure of the orbiter.

Looking through the top postings I wonder....

[ihatewinXP]

At a quick glance I see six top level postings as +5 Funny.

I wonder how many funny comments you can squeeze out of a space shuttle blowing up? And maybe who should I be more ashamed of, the people posting or the people moderating them all up?