NEWS: Failure Is Always an Option

Failure Is Always an Option

New York Times - August 29, 2003

By HENRY PETROSKI


URHAM, N.C. — Scientists seek to understand what is, the aerospace
pioneer Theodore von Kármán is supposed to have said, while engineers
seek to create what never was. The space shuttle was designed, at
least in part, to broaden our knowledge of the universe. To scientists
the vehicle was a tool; to engineers it was their creation.

With the release of the report of the Columbia Accident Investigation
Board, there is a new focus on the "culture" of NASA. Engineers have
played a prominent but not a controlling role in that culture, both in
the design of the shuttle and in the planning of its missions. When
the report speaks of NASA's "broken safety culture," the particular
failure it cites is "a consistent lack of concern" that Columbia may
have been damaged by debris at takeoff. But perhaps NASA can be better
understood by examining the culture that arises from the inevitable —
and healthy — tension among scientists, managers and engineers.

A common misconception about how things such as space shuttles come to
be is that engineers simply apply the theories and equations of
science. But this cannot be done until the new thing-to-be is
conceived in the engineer's mind's eye. Rather than following from
science, engineered things lead it. The steam engine was developed
before thermodynamics, and flying machines before aerodynamics. The
sciences were invented to explain the accomplishments — and to analyze
their shortcomings.

The design of any device, machine or system is fraught with failure.
Indeed, the way engineers achieve success in their designs is by
imagining how they might fail. If gases escaping from a booster rocket
can lower efficiency or cause damage, then O-ring seals are added. If
the friction of re-entry can melt a spacecraft, then a heat shield is
devised.

Much of design is thus defensive engineering: containing, shielding
and fending off anticipated problems on the drawing board and computer
screen so that they cannot bring down the design when it flies.
Obviously, total success can only come if every possible mode of
failure is identified and defended against.

Engineering is also very much about numbers. O-rings must be sized;
the thickness of heat shields specified; the weight of insulation
calculated. Often, the numbers work at cross purposes, as when
increasing shield material decreases available payload. Engineering
design is ultimately the art of compromise.

What results from the design process is a thing that has unique
characteristics. It can withstand the conditions for which it was
designed as long as it maintains its integrity. There is usually some
leeway allowed, for engineers know that operating conditions cannot be
predicted with absolute certainty. Until it fails, how far beyond
design conditions a system can be pushed is never fully known.

But engineers do know that nothing is perfect, including themselves.
As careful and extensive as their calculations might be, engineers
know that they can err — and that things can behave differently out of
the laboratory. On the space shuttles, O-rings got scorched, heat
tiles fell off, foam insulation broke free. To engineers, these
unexpected events were incontrovertible evidence that they did not
fully understand the machine.

Engineers do not feel comfortable with things they do not understand.
It is at this point that they begin to act more like scientists. In
the case of the scorched O-rings, the engineers studied burn patterns.
They looked for a correlation between damage and temperature, and they
warned about launching when the temperature was outside the bounds of
their experience and scientific study.

If engineers are pessimists, managers are optimists about technology.
Successful, albeit flawed missions indicated to them not a weak but a
robust machine. When engineers and managers clashed over the 1986
Challenger launch, the managers pulled rank. In the case of Columbia,
engineers who worried about damage that the spacecraft may have
suffered during launch were ineffective in getting it properly
inspected before reentry.

No one knows a machine or its failure modes as well as the engineers
who created it, and even they know it only as well as it reveals
itself to them. Because they are so humbled by their creations,
engineers are naturally conservative in their expectations of
technology. They know that the perfect system is the stuff of science
fiction, not of engineering fact, and so everything must be treated
with respect.

The Columbia Accident Investigation Board has recommended that NASA
establish an independent Technical Engineering Authority. This would
put responsibility for technical matters where it rightly belongs —
with the engineers who, because they know how the space shuttle was
designed, also know best how it can fail. Without that knowledge,
another fatal accident is inevitable.


Henry Petroski, professor of engineering and history at Duke
University, is author of the forthcoming "Small Things Considered:
There Is No Perfect Design."


http://www.nytimes.com/2003/08/29/op...partner=GOOGLE

(Rusty B) wrote in
om:


Engineers do not feel comfortable with things they do not understand.
It is at this point that they begin to act more like scientists. In
the case of the scorched O-rings, the engineers studied burn patterns.
They looked for a correlation between damage and temperature, and they
warned about launching when the temperature was outside the bounds of
their experience and scientific study.



You go on and on about the engineers. The fact is engineers are only
doing what mangement allows. It my understanding the O-ring failure in
many ways is a poltical one. They could have been built as one part.
They was a company in Florida that could do it at the time. But politcal
decisions wanted it bulit else where. The politicans want a piece of the
action. The current plane dsign with its stability problems is not what
an engineer would like. The russians tried that and realized its to
unstable and costly. The russian design is a lot safer and forgiving on
reentry. But the policicans care not about cost or safty. I vote we go
with a modifed russian desing for a while. The point is to get up and
back safely. The fly like an airplane in the atmosphere is not needed.
And if its totaly built in florida so be it. Build the parts where needed
don't just give each state a cut of the pie.


David A. Scott
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Disclaimer:I am in no way responsible for any of the statements
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Rusty B wrote:
: Failure Is Always an Option
:
All the non-engineers out there should read the first post in this thread=
..
If it hasn't already been posted to the political newsgroups it should be=
..=20

If the writer is a professor of History and Engineering at Duke, he
probably has a unique perspective on the inter-relationship of created
devices and the cultures in which they are developed and used. For instan=
ce,
why was it that the Chinese had gunpowder but never made a weapon out of =
it?


Parenthetically, hiring a non-engineer for a top management position at N=
ASA
is just as unwise as hiring a non-minister to be head of a church. Becaus=
e,
on certain critical matters, they simply won't know what's going on!
Why, for instance, did the Mission Manager not immediately realize that
a two-pound object at 500 mph has more than enough momentum to destroy
"fragile" and non-fragile protective tiles (or similar protective items.)
She and everyone around her should have been jumping out of their seats
when they first became aware of these numbers. But apparently they did
not make the simple mental calculations to see the power behind the hit.


Rev. Bill McGinnis
http://LoveAllPeople.org
"Everybody Should Love Everybody Else."


http://TheAmericanCitizen.US


: New York Times - August 29, 2003=20
:=20
: By HENRY PETROSKI
:=20
:=20
: URHAM, N.C. ? Scientists seek to understand what is, the aerospace
: pioneer Theodore von K=E1rm=E1n is supposed to have said, while enginee=
rs
: seek to create what never was. The space shuttle was designed, at
: least in part, to broaden our knowledge of the universe. To scientists
: the vehicle was a tool; to engineers it was their creation.
:=20
: With the release of the report of the Columbia Accident Investigation
: Board, there is a new focus on the "culture" of NASA. Engineers have
: played a prominent but not a controlling role in that culture, both in
: the design of the shuttle and in the planning of its missions. When
: the report speaks of NASA's "broken safety culture," the particular
: failure it cites is "a consistent lack of concern" that Columbia may
: have been damaged by debris at takeoff. But perhaps NASA can be better
: understood by examining the culture that arises from the inevitable ?
: and healthy ? tension among scientists, managers and engineers.
:=20
: A common misconception about how things such as space shuttles come to
: be is that engineers simply apply the theories and equations of
: science. But this cannot be done until the new thing-to-be is
: conceived in the engineer's mind's eye. Rather than following from
: science, engineered things lead it. The steam engine was developed
: before thermodynamics, and flying machines before aerodynamics. The
: sciences were invented to explain the accomplishments ? and to analyze
: their shortcomings.
:=20
: The design of any device, machine or system is fraught with failure.
: Indeed, the way engineers achieve success in their designs is by
: imagining how they might fail. If gases escaping from a booster rocket
: can lower efficiency or cause damage, then O-ring seals are added. If
: the friction of re-entry can melt a spacecraft, then a heat shield is
: devised.
:=20
: Much of design is thus defensive engineering: containing, shielding
: and fending off anticipated problems on the drawing board and computer
: screen so that they cannot bring down the design when it flies.
: Obviously, total success can only come if every possible mode of
: failure is identified and defended against.
:=20
: Engineering is also very much about numbers. O-rings must be sized;
: the thickness of heat shields specified; the weight of insulation
: calculated. Often, the numbers work at cross purposes, as when
: increasing shield material decreases available payload. Engineering
: design is ultimately the art of compromise.
:=20
: What results from the design process is a thing that has unique
: characteristics. It can withstand the conditions for which it was
: designed as long as it maintains its integrity. There is usually some
: leeway allowed, for engineers know that operating conditions cannot be
: predicted with absolute certainty. Until it fails, how far beyond
: design conditions a system can be pushed is never fully known.
:=20
: But engineers do know that nothing is perfect, including themselves.
: As careful and extensive as their calculations might be, engineers
: know that they can err ? and that things can behave differently out of
: the laboratory. On the space shuttles, O-rings got scorched, heat
: tiles fell off, foam insulation broke free. To engineers, these
: unexpected events were incontrovertible evidence that they did not
: fully understand the machine.
:=20
: Engineers do not feel comfortable with things they do not understand.
: It is at this point that they begin to act more like scientists. In
: the case of the scorched O-rings, the engineers studied burn patterns.
: They looked for a correlation between damage and temperature, and they
: warned about launching when the temperature was outside the bounds of
: their experience and scientific study.
:=20
: If engineers are pessimists, managers are optimists about technology.
: Successful, albeit flawed missions indicated to them not a weak but a
: robust machine. When engineers and managers clashed over the 1986
: Challenger launch, the managers pulled rank. In the case of Columbia,
: engineers who worried about damage that the spacecraft may have
: suffered during launch were ineffective in getting it properly
: inspected before reentry.
:=20
: No one knows a machine or its failure modes as well as the engineers
: who created it, and even they know it only as well as it reveals
: itself to them. Because they are so humbled by their creations,
: engineers are naturally conservative in their expectations of
: technology. They know that the perfect system is the stuff of science
: fiction, not of engineering fact, and so everything must be treated
: with respect.
:=20
: The Columbia Accident Investigation Board has recommended that NASA
: establish an independent Technical Engineering Authority. This would
: put responsibility for technical matters where it rightly belongs ?
: with the engineers who, because they know how the space shuttle was
: designed, also know best how it can fail. Without that knowledge,
: another fatal accident is inevitable.
:=20
:=20
: Henry Petroski, professor of engineering and history at Duke
: University, is author of the forthcoming "Small Things Considered:
: There Is No Perfect Design."
:=20
:=20
: http://www.nytimes.com/2003/08/29/op...D1062734400&e=
n=3D75c0dd6ec27f1277&ei=3D5062&partner=3DGOOGLE

--=20
Rev. Bill McGinnis
Editor - http://TheAmericanCitizen.US
Director - http://LoveAllPeople.org
Owner - http://FeaturedProducts.net=20


Bill McGinnis

"David A. Scott" wrote
[...]
And if its totaly built in florida so be it. Build the parts where needed
don't just give each state a cut of the pie.


This will probably happen when Florida has enough money to spend on the project.

/dps