Asbestos and the Challenger
Disaster
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The tragedy of the Challenger was that seven living representatives of the
American pioneer tradition were smashed to earth by political cowardice and
legal arrogance that destroyed the spaceship Challenger in the name of "Spaceship
Earth."
Michael J. Bennett p. 65
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Much has been written about the Challenger disaster and its causes.
Attention has focused on the aft (bottom) field joint of the right
solid rocket booster. The joint connected two sections of the booster;
because they are joined after the fuel was added the joint could not be sealed
or inspected from the inside. Instead the joint was sealed by a
rubber O-ring, and there was a secondary O-ring in case the first failed.
There were also a number of other components in the joint, including
putty which was intended to protect the O-rings from direct contact with
the hot exhaust gasses, and also act as a piston to pressurize the rings.
A small group of authors have focused on problems with the putty in
an attempt to blame the accident on various regulatory agencies. But
as we shall see there are serious problems with these claims. (For
more background information see the Challenger
disaster links.)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Because of an EPA ban on the use of asbestos, a non-asbestos containing putty
was substituted which didn't have the insulating fire-retardant powers of
asbestos.
Dixy Lee Ray, p. 178
What the public doesn't realize is that it is probably asbestos and the ban
on asbestos that caused the Challenger disaster. It wasn't the O-rings themselves
that failed. It was the putty that held the O-rings in place. Up until that
time, the time of the Challenger, that putty had had asbestos in it to strengthen
it and make it fire retardant. When the asbestos was removed, it was the
putty that gave way.
Ray in an interview
on C-SPAN in 1991
This doesn't even agree with what Ray's main source, Michael J. Bennett,
wrote (see the next section). The reality is that the EPA did
not ban any uses of asbestos till over three years after the accident
(see ban and
phaseout), and the putty that was used had been in use since the eight
flight (Challenger would have been number twenty five) and it contained asbestos
(Vaughn p. 5, Bennett p. 79)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[The astronauts] would have no way of knowing that a 1977 Consumer Product
Safety Commission ruling banning asbestos in certain paint products would
have a tragic effect on the flight. NASA had used an "off the shelf"
putty manufactured by the Fuller O'Brien Paint Company in
San Francisco to help seal the
field joints of the SRBs [solid rocket boosters] through the first ten missions.
Fuller O'Brien, fearful of legal action because of the ban, stopped
manufacturing the asbestos-based putty.
Joseph Trento p. 281
An excessive concern over the possible danger of asbestos in personal hair
dryers led directly to the crash of the space shuttle Challenger and the
deaths of its seven crew members..
A 1977 ban on asbestos in hair dryers triggered a series of decisions that
made unavailable the asbestos putty which had safely sealed the spaceship
engines, and led directly to the crash.
Bennett p. 65
On February 9, 1986 (the accident occurred on January 28) the New York
Times ran an article based on several memos that someone had sent them
(the article is reproduced in the Presidential Commission Report, Vol 4,
pages 269-270). This brought the "putty problem" (see the next section)
to the public's attention. While the article made no mention of the
change in putty, one of the memos, written by budget analyst Richard Cook,
did (it is reproduced in the Presidential Commission Report, Vol 4, page
273): "Engineers have not yet determined the cause of the problem.
Candidates include the use of a new type of putty (the putty formerly
in use was removed from the market by EPA because it contained asbestos),
failure of the second ring to slip into the grove which must engage it for
it to work properly, or new , and as yet unidentified, assembly procedures
at Thiokol." Trento (page 281) misquoted Cook,
changing the EPA to NASA, and stopped quoting at the first comma. (Bennett
(p.77) repeated the material as quoted by Trento,
which would tend to indicate that he did not check the original source.)
Trento does not tell the reader how he decided
it was the CPSC and not NASA that was responsible for the accident, or how
he determined that it was the putty and not some other part that failed.
Reading through Bennett's account
reveals several errors. On page 76 he wrote that events leading to
the accident "had begun with the CPSC ban on asbestos in paints, putties
and spackling compounds in 1977. The decision was prompted by news
stories, fanned by consumer groups, that asbestos could be found in many
products, including such innocuous items has (sic) hair dryers."
But the CPSC banned just two products, a type of spackling compound
and fake ashes that were sprinkled on fake fireplace logs. Both were
banned because they used tremolitic talc that was contaminated with asbestos.
Concern about asbestos in hair dryers did not begin until after this
ban, so it obviously could not be the cause (see
Key asbestos
findings since 1900,
RoC:
Asbestos).
And there never was any ban on asbestos in hair dryers, the CPSC got
manufacturers to voluntarily stop using asbestos in the dryers and to remove
it from existing dryers. Bennett, at least, quotes from a representative
of the company. (p 78) "'We didn't want any law suits,' explained
Tim Kelly, Fuller O'Brien's vice president for technology. 'We wanted asbestos
off the premises.'" The company would have been fearful of law suits
without any ban by the CPSC, and nowhere does Bennett include any mention
of the CPSC by Kelly. The ban may have influenced the company's decision,
but neither Trento nor Bennett make a credible case
that it did. In legal terms, the case would be dismissed due to lack
of evidence.
For more see Other claims of blame
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The putty protecting the critical O-rings in the Challenger's two booster
engines against the fiery rocket exhaust had been failing as far back as
1981 because of a lack of effective asbestos insulation
Bennett p 68
As early as 1981, the NASA engineers were becoming worried about erosion
marks seen on examination of the O-ring seals after the re-usable shuttle
returned from space missions.
Bennett p. 77
There was never any "lack of asbestos" but Bennett kept repeating this claim
(argument ad nauseam). But the interesting thing about these statements
is that in 1981 NASA was still using the original putty. Bennett even
notes this on page 78: "the company [Fuller-O'Brien] did make a
sufficiently large backlog of the putty to satisfy old customers such as
Morton-Thiokol [which assembled the boosters] up until 1983-1984 before shutting
down production.." The report by the Presidential commission confirms
this (page 125): "The manufacturer of the original putty, Fuller-O"
Brien, discontinued the product and a new putty, from the Randolph Products
company, was tested and selected in May 1982. The new Randolf putty
was eventually substituted for the old putty in the summer of 1983, for the
STS-8 Solid Rocket Motor flow." The chronology of O-ring problems (pages
129-131) shows that the first problem occurred during the second flight.
Problems also occurred with the nozzle joints on both boosters on flight
number 6 [these joints had a different configuration than the field joints
which connected the main parts of the booster. It was a field joints
that apparently failed on the Challenger.]. The boosters for flight
number 4 were not recovered, so it was not possible to inspect them for problems.
It is clear that the original putty was not the infallible substance
that Bennett claimed it to be.
The "putty problem' was that air pockets or blowholes would developed in
it. This would allow a jet of hot gasses to leak through (single point
infallible) and hit a small section (2 or 3 inches out of 37 feet) of the
primary O-ring causing it to burn or erode. It was feared that a primary
O-ring would erode enough to allow exhaust gases to leak through (on some
flights soot was found between the primary and secondary O-rings, showing
that blow-by had occurred. This could have been caused by erosion or
because the primary O-ring did not seal properly.) It was feared that
the secondary O-ring would also fail, and that the leaking exhaust gasses
would rapidly increase the size of the leak leading to disaster.
Starting with shuttle flight ten the "putty problem" started occurring on
almost every mission. At least part of this increase was apparently
caused by a change in a test procedure. To see if the O-rings were
properly sealed, the space between the primary and secondary rings was
pressurized. On the first seven flights 50 psi (pounds per square inch)
was used. Then the pressure was increased to 100 or 200 psi. Any
leak of the primary ring would pressurize the space between it and the putty.
This pressure could force the air through the putty. As Richard
Feynman (p 135) put it "Later in our investigation we discovered that it
was this leak check which was a likely cause of the dangerous bubbles in
the zinc chromate putty that I had heard about at JPL [Jet Propulsion
Laboratory]." Bennett quoted extensively from Feynman's book, so he
must have known about this change, but he does not let his readers know about
it. (The putty and the leak test are discussed at length in the
Presidential Commission report, p 64-66 and again on pages 133-134.)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[The Fuller O’Brien putty was] dubbed "lucky putty" by George Morefield
of United Technologies in a March
9, 1984 memo to NASA.
Bennett page 78
Morefield did call it "luck putty", but it was not meant as a complement.
From the memo,
reproduced on pages 246 and 247 of the presidential commission report:
The use of "lucky putty" has always been surrounded by controversy. Its
use has become a given, although no one really claims it to be part of either
the insulation system or the sealing system. In fact there is evidence
that it's use can cause problems other than forcing single-point infallible.
. . .
I recommend that you set up a panel to study the use of putty and consider
some alternatives:
1.) Is putty needed at all?
2) If the tradition can't be broken, can the putty be applied with multiple
(6 or 8) infallible paths built in?
There were a number of suggestions to correct the "putty problem", including
simply removing the putty
(Vaughan p 141). Bennett
quotes some of these suggestions to show that there was a problem with the
putty, but apparently it did not occur to him that these meant that the putty
might be unnecessary. The joints developed after the accident don't
use any putty ((Blumenthal, Anderson and Stever) and a test by the redesign
team indicated that the putty was not needed at all in the design used on
the Challenger. If the O-rings sealed properly, then the dead air space
where the putty would have been provided enough insulation to protect the
O-rings (page 677). Of course much more testing would have to be done
to show that the original design would work safely without any putty, but
this does show that "lucky putty" was not some irreplaceable substance.
(Bennett quotes from this article, but misinterprets it. Alas,
space allows a close look at just a few of the many errors Bennett
committed.)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Richard] Feynman submitted his findings, which highlighted the effect of
cold-and the lack of proper insulation which had been earlier provided by
asbestos-on the rubber in the O-rings.
Bennett: p. 69
What the [Consumer Product Safety Commission] did not take into account was
the far more real danger from fire and freezing that asbestos prevents.
These are only two of the dangers the putty was used to guard against
in sealing the O-rings on the Challenger, primarily preventing gases seeping
through cracks or blowholes.
Bennett p. 66
Feynman, of course, did not say anything about a "lack of proper insulation"
because there was never was such a beast. His only mention of asbestos
(page 122) was a comment that the engineers told him how much asbestos was
used in the liner between the joints.
But talk of cold brings us to what can be called the "O-ring problem".
When the boosters were designed, it was thought that the build up of
pressure during launch would squeeze the rubber O-rings, making the seal
tighter (Feynman page 133). Testing showed that the opposite happened,
as pressure built up the sections between the joints bowed out (termed joint
rotation) and the space that had to be sealed increased in width. The
O-ring had to expand to fill this gap, a process that took less than a second.
As Feynman noted, O-rings simply are not meant to work that way. At
normal temperatures the O-rings were able to increase rapidly enough, but
as the temperature decreased (which made the O-rings stiffer) problems increased
(Presidential Commission Report, page 146). The weather before the
Challenger launch was colder than before any previous launch. Several
engineers recommended that the flight be delayed, but they were overruled.
(Note: it was Feynman who brought the O-ring problem to the
public’s attention through his famous ice water experiment. He
put a piece of O-ring in a glass of ice water and then showed that it lacked
resilience when taken out.) (Note that Bennett seems confused about
the details; the cracks and blowholes were in the putty itself. It
is also clear that the putty was never meant to protect the O-rings from
cold from outside the boosters)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The truth wasn't covered up so much as it was ignored. It was ignored
because it demonstrated all too uncomfortably the inability of the system
to anticipate consequences of narrow political decisions taken to appease
clamoring interest groups.
Bennett p. 67
However, fear, ambition and power lust covered up the origin of the Challenger
crash because the
Washington establishment-not
just the top management of the NASA, but also the White House-really didn't
want to look too deeply.
Bennett p. 68
(There was no good reason for either NASA or the White House to protect the
CPSC. NASA, which was taking a great deal of heat, would have jumped
at the chance to shift even a small amount of the blame onto another agency.
And the anti-regulation Reagan administration had tried to shut down
the CPSC. Any link with the Challenger disaster would have given them
the ammunition they needed to do it.)
The most comprehensive study of the Challenger accident was that done by
the Presidential Commission appointed by Ronald Reagan (also known as the
Rogers Commission after its chairman, William Rogers). In addition
to the main report written by the commissioners there were four hefty volumes
of supporting data. Bennett apparently didn't even look at any of it.
Instead he reported what others, in particular commission member Richard
Feynman, had written about the report. While Feynman was critical of
some aspects of the commission, Bennett selectively quotes Feynman and provides
his own "interpretation" of his comments. Again looking at all of Bennett's
statements would take too much space. For those interested Feynman's
comments are in his book
What
do you care what other People Think.
In addition to the "putty problem" and the "O-ring" problem the commission
found several other problems that may have contributed to the accident.
One was a second putty problem. They found that the putty delayed
the initial infallible of the O-rings. Because the putty also became
stiffer as the temperature dropped this problem became worse as the temperature
decreased. Because the Commission only studied the
Randolph putty it is unclear
if the Fuller-O'Brien putty was better or worse in this respect. (The
Commission found that there were certain differences in the putties. In
particular, the Randolf putty was more susceptible to the environment. It
had to be kept cold and dry before being applied or it would become soft
and tacky.) The commission also found problems with the booster sections
being out of round. Because the boosters were shipped on there sides they
became elliptical rather than circular. Wear and tear caused dents
in the sections. This created difficulty in joining the sections together,
and the Commission found that it could also interfere with proper sealing
of the joints. Finally the Commission found several lapses in safety.
In a chapter titled "the Silent Safety Program" they reported these
lapses in safety. They also found that recommendations to delay the
launch until the weather became warmer were overturned. The decisions
leading up to the launch decision were detailed in a chapter titled ""The
Contributing Cause of the Accident." (They also reported that the booster
started to leak almost immediately. The first sign of a problem was
a series of smoke puffs that started less than a second after ignition.
That the booster started to leak almost immediately should prove beyond
a reasonable doubt that the accident had nothing to do with any "lack of
proper insulation.") The technical cause of the accident, according to the
Commission, was that there were too many problems with the joints for them
to work properly (p. 72):
In view of the findings, the Commission concluded that the cause of the
Challenger accident was the failure of the pressure seal in the aft field
joint of the right Solid Rocket Motor. This failure was due to
a faulty design unacceptably sensitive to a number of factors, These
factors were the effects of temperature, physical dimensions, the character
of materials, the effects of reusability, processing, and the reaction of
the joint to dynamic loading.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Safety Kills" is now a metaphor for the hubris, the inordinate pride, and
exaggerated self-importance of the environmental movement.
Bennett p. 67
But the real culprit was not rubber and putty. The pressure that really
caused the rocket booster to burst was political, not physical, and it came
from the unrelenting need to keep launching in order to justify the program.
William E. Burrows p. 558
The real tragedy of the Challenger disaster was that it was entirely preventable.
Most of the problems with the joints were known about years before
the accident, some were even recognized before the first shuttle flight.
(There were also a number of problems with the main rocket motors,
but most of these were solved before the fatal flight. (Feynman p.28)) But
fixing the problems would have meant even more delays in a program that was
already behind schedule. Instead of fixing the problems as they were
found NASA management rationalized that if the last flight succeeded then
the next one would too. NASA apparently violated both industry rules
and their own safety rules (Vaughn p. 33).. People were assigned
to solve the problems, but this activity was given a low priority. In
the meantime the engineers who worked on the shuttles were crying for help
((Feynman p. 185). And then there was the famous decision not to delay
the launch of the shuttle, in spite of the objections of a number of engineers.
This decision, again, was apparently made because the launches were
way behind schedule.
The real cause of the accident was not a lack of "lucky putty" but a lack
of concern for safety.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In Memoriam
Dick Scobey, Michael Smith, Ellison Onizuka, Judith Resnik, Ronald McNair,
Christa McAuliffe, Gregory Jarvis
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
References
Michael J. Bennett,
The
Asbestos Racket, Free Enterprise Press, 1991
Jack L. Blumenthal, Robert C. Anderson and H. Guyford Stever, "Rocket Motors
That Work", CHEMTECH, November 1989
William E. Burrows,
This
New Ocean: The Story of the First Space Age, The Modern Library,
1998
Richard P. Feynman,
What
do you Care What Other People Think: Further Adventures of a Curious
Character, Bantam Books, 1988
Dixy Lee Ray (with Lou Guzzo),
Environmental
Overkill: Whatever Happened to common Sense?, HarperPerennial,
1993
Report
to the President By the Presidential Commission on the Space Shuttle Challenger
Accident, 1986
Joseph Trento
Prescription
for Disaster: From the Glory of Apollo to the Betrayal of the
Shuttle, Crown, 1987
Diane Vaughan,
The
Challenger Launch Decision, The
University of
Chicago Press, 1996
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Written by
Jim
Norton
Visit my anti-environmental myths home page.
Visit my practical skepticism page
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