NASA blames disaster on foam

USA Today ^ | Posted 4/22/2003 5:02 PM Updated 4/23/2003 1:00 AM | Alan Levin and Traci Watson

[bvw]

It's all great fun to posit that "The Asbestos Nazis doomed the WTC and the Challenger too." And it's wrong. Deadly wrong.

There are a myriad --- thousands on thousands -- of unavoidable changes in parts, mixtures, manufacturers, environment that occur on a huge project such as the Shuttle. For example a cleaning agent, how it is used changes for this reason or that -- some reasons are noted, scrutinized, evalauted, approved, compensated, others not. Many changes go by unremarked, they may be too gradual to notice. For example one week you'll use an alchohol from manufacturer A, the next from manufacturer B. While both are to the spec, subtle important differences arise over time.

The ability of a system to gracefully handle all these changes, to handle an amount of out-of-spec-ness or accidents or all the unkhowns is called its "robustness".

The nature of the changes to the o-ring grease, the foam foaming agent, the metal cleaner were all small, the system actually was robust to them -- that is shuttles did fly and return with them in place. But these changes were problems, and they in fact gave clear signals that could have and should have been noticed in plenty of time. It is the failure to notice those signals -- to deal with problems early and often, rather than catastrophically late that is one of a pair of fatal flaws in the shuttle program.

"Enviromental lunacy" is NOT one of those flaws.

The first flaw, as Feynman noted, is that the shuttle program is too insensitive, too bureaucratic, too unresponsive in its bigness to such critical, yet small, signals. Responsibility is spread so far, so thin, that no one knows they have it! This is an incorrectable flaw.

The second fatal flaw is in the Shuttle system itself. While I showed that it was somewhat "robust" to the "enviromental wacko" inspired small changes, the thing that is clear to me, from following all the most excellent thread you and a small hard-working and careful group of Freepers have been running, is that overall the shuttle system is NOT robust at all. Too many things could kill one, and only hairy-ass luck has gained the safety record to date. It is more aguable that this is correctable, but, to me, that is a very weak argument. It is too big, too complex, too established, too expensive for corrections to work, even if some very very difficult still-outstanding technical issues were dealt with.

Anyway, my point is that blaming "enviromental wackos" for the shuttle failure is like blaming the weatherman for your getting stuck in the snow, because he didn't predict a heavy snowfall. A loser excuse.

[Dead Dog]

Actually, the O-ring wasn't a flaw..launching the vehicle after it had cold soaked and was below operating spec was.

Your point is well taken, it is a complex organization, and the SCD complience is difficult or impossible to enforce 100%, and even the SCDs don't envelope all possible failures.

And that is the reason changing a functional material, that has no proven replacement, for reasons based in junk science is bad policy. A policy pushed by the Asbestos and CFC Nazis.

They need to be held accountable.

[Captain Beyond]

Bump

[Bobby777]

you got that right ... several of us were derided as such ...

[Jael]

I know we all hated to be right about this. Wonder where all the stalkers and bashers and haters of truth are now? Probably spending all their energy freeping Dixie Chricks polls.

[TLBSHOW]

I know we all hated to be right about this.

As we said the truth would come out. As for the other part of your post they are all over at a thread supporting the trashing of the second amendment and at another thread supporting a socialist.

[fooman]

There are STILL people that discount the problems that the engineers were asserting with models.

The models were developed with certain assumptions in mind. When those assumptions do not hold up years later...

[TLBSHOW]

sad really when people are getting killed over assumptions.

[fooman]

Well said on the enviros!

And I might add that we should not even think about kyoto until the rest of the world adopts the ban on CFCs

[fooman]

Robustness and spec changes are two different issues.

While we would like all future version of the shuttle to be more robust as you define it, you do not change items without regression testing. Basic systems engineering concept.

IF the freon free did not delivery the same performance, it should not have been used. Period.

[fooman]

Notice that the article does not mention WHY the foam was falling of more.....

But the debris field oritntation, photo of impact, wing temps and order of sensors lost is daming....

[bvw]

Did that freon-free stuff meet the spec? I mean, what I am saying is re "robustness" is that the specifications are finite, limited, uncognizant of actual complex reality beyond those very few words and numbers that make up a spec.

The new stuff, a new batch from a new lot of stuff meets the spec. Yet within the consraints of that spec, things can vary manufacturer to manufacturer, lot to lot, etc. There is a robustness of how well a system responds to variances within spec. Those variances can occur both to qualities and quantities specified, and things unknown, unspecified.

At what level of change does regression testing come into play, and what level of regression testing? If a system like a shuttle is fully regression tested every time a new lot of machine bolts comes in, it would never make any launch date even a millenium from now.

Let me mention responsibility.

Specs are absolutely irresponsible. Responsibility is only a property of men -- not specs. A responsible group of men put the spec together in a responsible fashion, but they did not by so doing create responsibility. Checking off a a cheklist, running every regression test in the book and then some, does not create responsibility.

Responsibility is always and ever a human judgement call. Tools such as specs, procedure, and regression testing can *help* make responsible decisions. Yet every dang tool is only a tool has no inherent responsibility by being or by being used.

And -- here a stat case -- the very tools that were employed to help make responsible decisions, ended up greatly contributing to making utterly irresponsible decisions. As long as process and procedure was followed -- that was held to be "responsible". Well it was not. It was instead massively, catastrophically, unredeemably irresponsible.

[fooman]

I don't know where to start with this because your response has lots of individual elements and issues which have merit.

The foam change obviously did not meet spec-- that is the issue. And ordninarily one would not even make the change here, since the old foam had a long track record.

This change was made to win PC enviro awards. IF you are the engineer in the program ( I used to do telemetry) there is intense pressure to go along with the groupthink and not push for the exception. Thats what people have a beef with around here.

If you want to use a solution that could obviously have an impact on the whole system, then you need to test the bonding characteristics at the black box level and then at the system level. Yeah its boring and frustrating, but believe me, we spent a LOT of time doing this.

I am sympathetic with your idea that people were laying off responsiblity to static requirements (often a misnomer) and specs.

They are tools to gain consistency and repeatability. And yes, it sometimes is an auditing issue in terms of what process of assumptions creates these design paramenters.

In this case the assumptions around HOW to use the modeling tools were lost and the young engineers(along with management) got a false sense of security using tools beyond itended parameters...

[icwhatudo]

Wait a sec...Were we wrong?

From a friend:

Yesterday, Volume 1 from the Columbia Accident Investigation Board was issued. On page 129 of that report, the following was stated: "The change in blowing agent affected only mechanically applied foam. Foam that is hand sprayed, such as on the bipod ramp, is still applied using CFC-11."

On page 9 of the report (Executive Summary Section), the following was stated: "The physical cause of the loss of Columbia and its crew was a breach in the Thermal Protection System on the leading edge of the left wing, caused by a piece of insulating foam which separated from the left bipod ramp section of the External Tank at 81.7 seconds after launch, and struck the wing in the vicinity of the lower half of Reinforced Carbon-Carbon panel number 8."

Love to prove him wrong but in our haste to blame the enviros, could WE be wrong?