1986: Challenger Space Shuttle Explosion 71
One year later, NASA submitted a report detailing all the actions taken to
meet these recommendations (NASA, 1987). The first shuttle flight after the
Challenger explosion was Discovery’s launch on September 29, 1988.
The space shuttle program is the major segment of NASA’s National
Space Transportation System (NSTS). It is divided into four levels:
Level I: NSTS director, responsible for the overall program
requirements, budgets, and schedules.
Level II: NST program manager, responsible for shuttle program
baseline and requirements. Provides technical oversight on behalf of
Level I.
Level III: Program managers for orbiter, solid rocket booster, external
tank, and space shuttle main engine, responsible for development,
testing, and delivery of hardware to launch site.
Level IV: Contractors for shuttle elements, responsible for the design
and production of hardware.
Prior to 1983, Level III was required to report all problems, trends, and
problem closeout actions to Level II, unless a hardware-associated problem
was not flight critical. However, a control board directive, submitted by
Martin Raines, director of safety, reliability and quality assurance at
Johnson, and signed by Level II on March 7, 1983, reduced the scope of
reportable problems to Level II. The revised scope included only those
problems that dealt with common hardware items or physical interface
elements, and eliminated reporting on flight safety problems, flight schedule
problems, and problem trends. According to a memo Mr. Raines wrote to
the commission during its investigation in 1986, the documentation change
was made in an attempt to streamline the system, because the old require-
ments were not productive for the operational phase of the shuttle program
(Rogers Commission, 1986).
This document, Space Shuttle Program Requirements Control Board
Directive 501152A, could not be obtained from public records.
Thiokol engineer Roger Boisjoly inspected hardware from Flight 51C
after it returned. This flight had been launched on January 14, 1985, during
the coldest ambient temperature to date. Boisjoly found that hot combustion
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72 Engineering Ethics: An Industrial Perspective
gases had blown by the primary seals on two field joints and had produced
large arc lengths of blackened grease between the primary and secondary
seals. Based on this discovery, he hypothesized that the low ambient tempera-
ture (resulting in a 53° F O-ring temperature) prior to launch caused reduced
O-ring resiliency, which was responsible for the excessive blow-by. Further
O-ring bench testing confirmed his hypothesis. Boisjoly became part of the
Thiokol O-ring investigation task force formed in August 1985 (Boisjoly,
The night before the launch of Flight 51-L, because of Thiokol’s con-
cern that the launch would occur at temperatures in the low twenties,
Thiokol scheduled a teleconference between Thiokol and NASA shuttle
personnel at the Kennedy Space and Marshall Space Flight Centers.
During this teleconference, Boisjoly presented his O-ring data, and
Thiokol management recommended that the launch not occur until
O-ring temperature reached at least 53° F, which was the lowest temper-
ature of any previous flight. George Hardy, the Deputy Director of
Science and Engineering at Marshall, was reported to have been
“appalled” by Thiokol’s recommendation (Rogers Commission, 1986)
but could not launch over the contractor’s objection (Boisjoly, 1987).
Immediately thereafter, while NASA asked for a private caucus, Thiokol
managers attempted to make a list of data to support a launch decision.
The Thiokol engineers witnessed Senior Vice President Jerry Mason ask
Vice President of Engineering Bob Lund to “take off his engineer hat
and to put on his management hat” (Rogers Commission, 1986; Boisjoly,
1987). When the three groups reconvened their teleconference, Thiokol
stated that although temperature effects were a concern, data were
inconclusive, so a launch was recommended.
The temperature data of flights with O-ring incidents, which were
presented by Boisjoly at the teleconference, are shown in Figure 5.3. When
all flight data are added to the plot, including flights with no erosion or
blow-by (see Figure 5.3), it becomes clear that reduced O-ring resiliency
had occurred in every flight associated with a joint temperature less than
65° F (Rogers Commission, 1986).
After Boisjoly testified at the shuttle presidential commission, he expe-
rienced a hostile work environment at Thiokol. He was given an extended
sick leave and then long-term disability for 2 years (Boisjoly, 1987). In
1988, Boisjoly received the American Association for the Advancement of
Science’s Scientific Freedom and Responsibility award “for his exemplary
and repeated efforts to fulfill his professional responsibilities as an engi-
neer by alerting others to life-threatening design problems of the
Challenger space shuttle and for steadfastly recommending against the
tragic launch of January 1986” (AAAS, 2005).
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