challenger failure(1)

8/2/2019 Challenger Failure(1)

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Peter Hadreas, Professor of Philosophy

Campus phone: 924-1376Email: [email protected]

Office location: 210 Faculty Office Bldg.

Engineering 10-11, Spring, 2009
mailto:[email protected]:[email protected]


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Oftentimes they seem to be hardchoices or moraldilemmas. There,you are pulled between twoconflicting professional goals:

It appears you have to choosebetween the lesser of two evils.


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The Challenger Disaster citedin the first lecture.

Today well consider one more

case.

This time it will be a famous

case and a national disaster:


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The crew of Space Shuttle, Challenger. MichaelJ. Smith, Dick Scobee and Ronald McNair (frontrow from left to right). Ellison Onizuka, ChristaMcAuliffe, Gregory Jarvis, and Judith Resnic

(back row, left to right).


7/58Liftoff of Challenger


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The primary component of thevehicle was the Orbiter, the

reusable, winged craft containingthe crew that actually traveledinto space and return to land on

a runway.

Challenger disaster photos copied and text adapted fromAerospaceweb.org (2004) Space Shuttle ChallengerDisaster, Retrieved November 3, 2008 Aerospaceweb.org,

Web site:http://www.aerospaceweb.org/question/investigations/q012


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Orbiter containing flight deck andcrew


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However, the Orbiter alone did

not generate enough thrust orcarry enough fuel to get intoorbit. The additional thrust was

provided by the two large SolidRocket Boosters, each attachedto the side of the External Tankby means of two struts.

Photos copied and text adapted from Aerospaceweb.org(2004) Space Shuttle Challenger Disaster, Retrieved

November 3, 2008 Aerospaceweb.org, Web site:http://www.aerospaceweb.org/question/investigations/q012


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Left Solid

RocketBooster

Right SolidRocketBooster


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Once the two solid rocket

boosters lifted the Shuttle to analtitude of about 45,760 m(roughly 28.4 miles), they would

be jettisoned.


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External Tank

Three mainengines of theorbiter


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Challenger disaster diagrams copied and text adapted from Aerospaceweb.org(2004) Space Shuttle Challenger Disaster, Retrieved November 3, 2008Aerospaceweb.org, Web site:

http://www.aerospaceweb.org/question/investigations/q0122.shtml

Two-thirds of the External Tank tank was filled with liquid hydrogen; thetop third with liquid Oxygen. This fuel supplied the three main engines

of the Orbiter until about 8 1/2 minutes after liftoff. Then the ExternalTank would be jettisoned at about 111,355m (roughly 69.2 miles) .


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Disintegration of the shuttle occurred 73seconds into its flight.


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73 seconds after lift-off, smoke was seen billowingout from the right solid rocket booster followed by

several explosions.


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Why did the shuttle explode anddisintegrate?


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The segments of each booster was

joined into three major sections. Thesections were interlocked by what isknown as a tang and clevis joint.


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The Tang and Clevis

joints used tointerlock thesegments of thesolid rocket boosters


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The tang and clevis joint is sealed bytwo rubber O-rings. Through the heat

generated by the burning propellantfrom the boosters, these rubber sealsexpand to fill the joints of the threesections and prevent the hot exhaust

from escaping.

Challenger disaster photos copied and text adapted from

Aerospaceweb.org (2004) Space Shuttle ChallengerDisaster, Retrieved November 3, 2008 Aerospaceweb.org,

Web site:http://www.aerospaceweb.org/question/investigations/q012


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O-rings whichexpand from

the heat of theburning fueland seal thesection joints.


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This picture was taken on the morning of theChallenger launch January 28, 1986. This wasthe coldest day in history that a shuttle had

been launched.


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The O-ring seal in the right solid rocketbooster failed to remain sealed.

The O-ring failure allowed a flare of

pressurized hot gas from the solid rocketmotor to melt the attachment hardware -- thestrut -- and to ignite the liquid hydrogen andoxygen in the external fuel tank.


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The Challenger explosion arose fromintense heat spurting through a joint inthe

a. external tank.b. the orbital, the vessel that

contained the crew.

c. the solid rocket booster.d. the lift-off rigging.e. the crews quarters.

Question


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Roger Boisjoly, chief O-ring engineer at Morton

Thiokol, had warned his colleagues that O-ringslose their resiliency at relatively low

temperatures.


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Jerald Mason was senior vice

president at Morton Thiokol wherekey Challenger engineers, includingRoger Biosjoly worked.

Mason learned the engineers couldnot supply firm figures regarding

what temperatures would be unsafeto launch the Challenger.


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Jerald Mason told Morton Thiokolsupervising engineer, Robert Lund:take off your engineering hat and

put on your management hat.

Rogers Commission, Report to the President

by the Presidential Commission on the SpaceShuttle Challenger Accident(Washington, D.C.: June 6, 1986), pp. 772-773.


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Without firm figures that determine

that the launch was unsafe, theearlier recommendation to delaythe launch was reversed.


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Some professional goals or virtuesof engineers:

upholding high standards of professionalcompetence and expertise,

holding paramount the health, safety andwelfare of the public.


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Some professional goals or

virtues of managerial decision-makers:

Maximizing the well-being of the organization orcorporationin question. This includes costs, marketingand public relations.

Upholding organizationalemployee moraleand welfare.


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In the Challenger disaster therewas again a moral dilemma.

As we have seen in the previous threeclasses, it again involved a conflict inprofessional goals.


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But the conflict was between

managerial obligations andengineering goals.

The engineers wanted to ensurethe safety of the launch. At thesame time they wanted to be

faithful agents of their employer,Morton Thiokol.


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There tends to be a conflictbetween engineering and in

managerial professionalgoalsor virtues.

In particular, the engineering decisionsregarding safety issueswill have a differentfoundation from managerial decisionsregarding safety.

The engineers decision will tend to extenddirectly to the well-being of the public.The managers decision will tend to extend

more to the well-being of the organizationtheywork for.


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Lets return to the challenger case.

The failure and explosion of the

Challenger was due to the lack ofresiliency of the O-rings under coldtemperature. But the reasons for

the cold temperatures were actuallycomplex.


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As a matter of fact, an usually stiff blewtowards the west-northwest on the night

preceding the launch. As a result, the

super-cooled air around the liquidhydrogen and liquid filled external tankflowed directly into the lower portion of

the right solid rocket booster and cooledthe lower joint.


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Wind blowing over the External Tank and impinging on the aft field

(lower) joint of the right Solid Rocket Booster.


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But even the unusual direction of thecold wind, deflecting off the External

tank and the extremely low day-timetemperature on the day of the launchwas not enough to make the O-rings

fully malfunction.

The following Challenger disaster photos copied and text adapted fromAerospaceweb.org (2004) Space Shuttle Challenger Disaster, RetrievedNovember 3, 2008 Aerospaceweb.org, Web site:

http://www.aerospaceweb.org/question/investigations/q0122.shtml


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If the very low day-time temperature onJanuary 28, 1986 and the usually coldwest-northwest wind were enough to

make the O-rings malfunction, the shuttlewould have exploded within a fewseconds after take-off. But thats not what

happened. Severe problems did notoccur until 50 seconds after take-off.


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This didnt happen until 56 seconds into thelaunch, right around the time max Q.

Max Q is the point of maximum air

pressure upon the ascending shuttle. It isdetermined by the relation betweenincreasing acceleration of the missile andthe decreasing density of the atmosphere as

the shuttle ascends.

Right around the time of Max Q the Challenger passed

through the worst wind shear in the history of the Shuttleprogram.

So in fact there was another unexpected risk factorwhich caused the O-rings to fully malfunction.


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A very low daytime temperature on the dayof the launch. Mortol Thiokol engineers hadno significant data at how O-rings wouldperform below 51 F (11C).

The worst wind shear in the history of the Shuttle programat 56 seconds into the launch, the time of Max Q.

So there were three causes which caused the O-rings to malfunction on the day of the Challengerlaunch:

An unusual strong west-northwest wind that ledunusually cold air to be deflected off the liquid hydrogenand oxygen tank onto the right lower O-joint.


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So how does this review of thecauses of the Challenger Disaster

add to our understanding of ethicalproblem-solving in engineering?


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It obviously underscores the seriousconsequences that can ensue from poor

ethical decision-making.


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In particular, with the ChallengerDisaster we learn that in engineering

ethics a conflict often arises betweenengineeringprofessional goals and

managerialprofessional goals.


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In particular we learn that for engineers,the determination of risk to the health,

safety and welfare of the public is acrucial consideration.

As risk expert William W Lowrance


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As risk expert William W. Lowranceexplains determining risk is acompound measure of magnitude and

adverse effect(Lowrance. 1980).

Lowrance, William W. (1980). The Nature of Risk. In RichardC. Schwing and Walter A. Albers, Jr., eds. Societal RiskAssessment: How Safe Us Safe Enough?New York: Plenum

Press, p. 6.


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It becomes clear, then, that determining

the probabilities of safety risk of asystems components -- such as theSolid Rocket Boosters O-rings --

requires a degree of error indetermining the likelihood of adverseeffects.


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When Jerald Mason, the high-levelmanager at Morton Thiokol, learned

that engineers, including RogerBiosjoly, could not supply firm

figures regarding at whattemperatures the Challenger launchwould be unsafe, he was asking the

wrong question.Why?


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In the cases weve consider before,

weve frequently seen that ethical

dilemmas often appear as a hardchoice. You have to choose betweenthe lesser of two evils.

In the Challenger disaster, the lesser oftwo evils choice should have been todelay the launch.


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Can you suggest a middle waysolutionbetween the disastrousdecision to launch the Challenger onJanuary 28, 1986 and to postpone it?

The creative middle way solutionshould address both the goal of

eliminating the risk of themalfunctioning O-joints and at thesame time allow NASA to keep its

commitments for on-schedule

A final question


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Final Summary

Ethical problem solving, whether personal orprofessional, strives to find a creative ways to

Virtues or ethical goals arise from responsesto the human condition which balance theexcesses and deficiencies of human needs.

Engineering professional goals or virtues, suchas protecting public safety and client andemployee honesty, lead to the trust and

progress of the engineering profession

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