The Challenger Launch Decision: Risky Technology, Culture, and Deviance at NASAby Diane Vaughan
When the Space Shuttle Challenger exploded on January 28, 1986, millions of Americans became bound together in a single, historic moment. Many still vividly remember exactly where they were and what they were doing when they heard about the tragedy. In The Challenger Launch Decision, Diane Vaughan recreates the steps leading up to that fateful decision,/i>… See more details below
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When the Space Shuttle Challenger exploded on January 28, 1986, millions of Americans became bound together in a single, historic moment. Many still vividly remember exactly where they were and what they were doing when they heard about the tragedy. In The Challenger Launch Decision, Diane Vaughan recreates the steps leading up to that fateful decision, contradicting conventional interpretations to prove that what occurred at NASA was not skulduggery or misconduct but a disastrous mistake.
Journalists and investigators have historically cited production problems and managerial wrong-doing as the reasons behind the disaster. The Presidential Commission uncovered a flawed decision-making process at the space agency as well, citing a well-documented history of problems with the O-ring and a dramatic last-minute protest by engineers over the Solid Rocket Boosters as evidence of managerial neglect.
Why did NASA managers, who not only had all the information prior to the launch but also were warned against it, decide to proceed? In retelling how the decision unfolded through the eyes of the managers and the engineers, Vaughan uncovers an incremental descent into poor judgment, supported by a culture of high-risk technology. She reveals how and why NASA insiders, when repeatedly faced with evidence that something was wrong, normalized the deviance so that it became acceptable to them.
No safety rules were broken. No single individual was at fault. Instead, the cause of the disaster is a story not of evil but of the banality of organizational life. This powerful work explains why the Challenger tragedy must be reexamined and offers an unexpected warning about the hidden hazards of living in this technological age.
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The Challenger Launch Decision
Risky Technology, Culture, and Deviance at NASA
By Diane Vaughan
The University of Chicago PressCopyright © 1996 The University of Chicago
All rights reserved.
THE EVE OF THE LAUNCH
NASA's Space Shuttle Challenger originally was scheduled for launch January 22, 1986. A crew of seven was assigned. Commander Richard Scobee, Pilot Michael Smith, and Mission Specialists Ellison Onizuka, Judith Resnik, and Ronald McNair were astronauts. Gregory Jarvis, an aerospace engineer, and Christa McAuliffe, a teacher from New Hampshire, were payload specialists. McAuliffe's assignment—to teach elementary school students from space—gave the Challenger a special aura. Officially known as Space Transportation System (STS) mission 51-L, it became publicly identified as the "Teacher in Space" mission, despite the scientific and technical assignments of the other crew members. According to plan, Challenger would be the first launch of 1986. However, the launch date had to be "slipped" several times—first to January 23, then to January 25, then to January 26—because seven launch delays over a 25-day period postponed the December launch of Columbia (STS 61-C). Setting a NASA record for false starts, STS 61-C was launched January 12.
Efforts for the January 26 Challenger launch from Kennedy Space Center, Cape Canaveral, Florida, were coordinated by the top technical managers and administrators in NASA's four-tiered launch decision chain. Among them were Jesse Moore, Associate Administrator for Space Flight, NASA Headquarters, Washington (Level I); Arnold Aldrich, Program Manager, Johnson Space Center, Houston, Texas (Level II); William Lucas, Director, Marshall Space Flight Center, Huntsville, Alabama; Stanley Reinartz, Manager, Shuttle Projects Office, Marshall; Lawrence Mulloy, Manager, Solid Rocket Booster Project, Marshall (Level III); and Allan McDonald, Director, Solid Rocket Motor Project, Morton Thiokol, Utah (Level IV). Following Columbia's precedent for delay, early countdown activities were terminated because the forecast indicated that weather at Kennedy would be unacceptable throughout the launch window. NASA rescheduled for January 27. That day, countdown was proceeding normally when microswitch indicators showed that the exterior hatch-locking mechanism had not closed properly. By the time it was fixed, the wind velocity exceeded the Launch Commit Criteria for allowable crosswinds at the Kennedy Space Center runway used in case of a return-to-launch-site abort. The launch was scrubbed at 12:36 P.M. and rescheduled for January 28 at 9:38 A.M. EST.
NASA personnel at the Cape first became concerned about cold temperature at approximately 1:00 P.M. on January 27. The forecast for the eve of the launch predicted clear and uncharacteristically cold weather for Florida, with temperatures expected to be in the low 20s during the early hours of January 28. Marshall's Larry Wear, Solid Rocket Motor Manager, asked Morton Thiokol- Wasatch, in Utah, manufacturer of the Solid Rocket Motor (SRM), to have its engineers review the possible effects of the cold on the performance of the SRM. This was not the first time concerns about SRM performance had been raised between Marshall and Thiokol. On several previous launches, hot combustion gases produced when the propellant ignited at liftoff had charred and sometimes even eroded the surface of the rubberlike Viton O-rings designed to seal the joints between the SRM case segments of the Solid Rocket Boosters (SRBs) that help get the shuttle off the launch pad and into the sky (see figs. 1, 2, & 3).
In response to Wear's inquiry, Thiokol's Robert Ebeling, Ignition System Manager, convened a meeting at the Utah plant. The Thiokol engineers expressed concern that the cold would affect O-ring resiliency: the rings would harden to such an extent that they would not be able to seal the joints against the hot gases created at ignitior, increasing the amount of erosion and threatening mission safety. A three-location telephone conference to discuss the situation was set for 5:45 P.M. EST. Participating were some of the managers and engineers associated with the SRB Project located at Thiokol, Marshall Space Flight Center, and Kennedy Space Center. During the teleconference, Thiokol expressed the opinion that the launch should be delayed until noon or after. A second teleconference was arranged for 8:15 P.M. EST so that more personnel at all three locations could be involved and Thiokol engineering data could be transmitted by fax to all parties.
Thirty-four engineers and managers from Marshall and Thiokol participated in the second teleconference see appendix B, fig. B1). Thiokol engineers in Utah presented the charts they had faxed containing their technical analysis of the situation. They argued that O-ring ability to seal the booster joints at ignition would be slower at predicted temperatures than on the coldest launch to date: a January 1985 mission when the calculated O-ring temperature was 53F. On that flight, hot propellant gases had penetrated a joint, eroding a primary O-ring to such an extent that it had not sealed at all, allowing the hot gases to "blow by" the primary toward the secondary O-ring.
Reinartz then asked Kilminster for comments. Kilminster requested a five-minute off-line caucus for Thiokol managers and engineers in Utah. The caucus continued for about 30 minutes, during which all three sites were on mute. In Utah, after some discussion, Thiokol Senior Vice President Jerry Mason said, "We have to make a management decision," thus excluding Thiokol engineers from the decision making. Included were four senior Thiokol managers—among them Robert Lund, who had supported the engineering position. Engineers Arnie Thompson and Roger Boisjoly again tried to explain the engineering position. Thompson sketched the joint and discussed the effect of the cold on the O-rings. Showing photographs of the rings on the two flights with blow-by, Boisjoly argued for the correlation between low temperature and hot-gas blow-by. Getting no response, Thompson and Boisjoly returned to their seats. The Thiokol managers continued their discussion and proceeded to vote. Three voted in favor of launch; Lund hesitated. Mason asked him to "take off his engineering hat and put on his management hat." Lund voted with the rest.
The off-line caucus over, the second teleconference resumed. Kennedy and Marshall came back on line. Thiokol's Joe Kilminster announced that Thiokol had reconsidered. They reversed their first position, recommending launch. Kilminster read the revised engineering analysis supporting the recommendation. Mulloy requested that Kilminster fax a copy of Thiokol's flight-readiness rationale and launch recommendation to both Kennedy and Marshall. The teleconference ended at about 11:15 P.M. EST. At Kennedy, McDonald argued on behalf of the Thiokol engineering position. Subsequently, Mulloy and Reinartz telephoned Aldrich, discussing the ice that had formed on the launch pad and the status of the recovery ships. They did not inform Aldrich about the teleconference and Thiokol engineers' concerns about the effects of cold temperature on the O-rings. The Kennedy Space Center meeting broke up about midnight.
At 1:30 A.M. on January 28, the Ice/Frost Inspection Team assessed the ice on the launch pad. NASA alerted Rockwell International, prime contractor for the Orbiter in Downey, California, where specialists began investigating possible effects of ice on the Orbiter. Reporting for launch at 5:00 A.M., Mulloy and Reinartz told Marshall Director Bill Lucas and James Kingsbury, Director of Marshall's Science and Engineering Directorate, of Thiokol's concerns about temperature and the teleconference resolution. At approximately 7:00 A.M., the ice team made its second launch pad inspection. On the basis of their report, the launch time was slipped to permit a third ice inspection. At 8:30, the Challenger crew were strapped into their seats. At 9:00, the Mission Management Team met with all contractor and NASA representatives to assess launch readiness. They discussed the ice situation. Rockwell representatives expressed concern that the acoustics at ignition would create ice debris that would ricochet, possibly hitting the Orbiter or being aspirated into the SRBs. Rockwell's position was that they had not launched in conditions of that nature, they were dealing with the unknown, and they could not assure that it was safe to fly. The Mission Management Team discussed the situation and polled those present, who voted to proceed with the launch.
A little after 11:25 A.M., the terminal countdown began. STS 51-L was launched at 11:38 A.M. EST. The ambient temperature at the launch pad was 36F. The mission ended 73 seconds later as a fireball erupted and the Challenger disappeared in a huge cloud of smoke. Fragments dropped toward the Atlantic, nine miles below. The two SRBs careened wildly out of the fireball and were destroyed by an Air Force range safety officer 110 seconds after launch. All seven crew members perished.
THE SEARCH FOR AN EXPLANATION: CREATING HISTORY
The grief and shock that encompassed the millions who witnessed the tragedy intensified in its dramatic aftermath. In early February, President Reagan created a commission, headed by former Attorney General William P. Rogers, to investigate the disaster. Within 120 days, the Presidential Commission (also called the "Rogers Commission") was to submit a report to the President that established the probable cause or causes of the technical failure and was to make recommendations based on its findings. NASA had already begun its own investigation of the tragedy; the Presidential Commission saw its role as one of collaborative oversight. Subsequently, however, the Commission's search for an explanation uncovered evidence that placed NASA managers and the launch decision at the center of controversy. Grief and shock were joined with public incredulity and outrage as the Commission discovered information revealing that the disaster might have been avoided. Unraveling the history of decision making between Marshall and Thiokol about the SRBs in its televised hearings, the Commission incrementally laid the groundwork for what became the historically accepted explanation of the Challenger launch decision: production pressures and managerial wrongdoing.
The Commission's televised hearings began on Thursday, February 6, 1986. Witnesses testified under oath. The first business was to bring the Commission up to date on NASA's in-house investigation. Associate Administrator for Space Flight Jesse Moore showed photographs of Challenger in flight revealing what appeared to be a flame coming from the right SRB at the aft segment. He said, "We don't know for sure it is the SRB. I will caution you, it appears in that area, but we are not ruling out anything at this point." Neither he not others pointed definitively toward the O-rings as the probable cause of the tragedy. In fact, Jud Lovingood, Deputy Manager, Shuttle Projects Office, Marshall, downplayed the O-rings as a potential cause. He testified: "We have seen some evidence of what we call blow-by of those seals, some erosion of those seals. The primary seal. We have never seen any erosion of a secondary seal, but we have seen evidence of soot in between the two seals." However, Lovingood said tha: problem had been "thoroughly worked" and offered to provide the Commission with the paperwork documenting the engineering analysis. When asked whether the effect of the cold weather on the SRBs was a concern, Lovingood testified: "We did have a meeting with Thiokol. We had a telecon discussion with people in Huntsville, people at the Wasatch division, and people at KSC [Kennedy Space Center]. And the discussion centered around the integrity of the O-rings under lower temperature. We had the Project Managers from both Marshall and Thiokol in the discussion. We had the chief engineers from both places in the discussion. And Thiokol recommenced to proceed on the launch, and so they did recommend the launch."
In the next session, Moore presented additional photographs and the first results of flight data analysis indicating a time correlation between the plume approximately at the aft field joint in the photographs and the telemetry data on the Challenger's increasingly erratic flight performance. Both Moore and Aldrich acknowledged the possible significance of cold weather on the sealing capability of the O-rings. The weather, O-ring erosion, putty performance, and Rockwell's concern about the ice became a focus of the Commission's questions that day.
Then, on February 9, the Sunday New York Times ran a front-page story headed, "NASA Had Warning of a Disaster Risk Posed by Booster." Quoting from internal NASA documents released to the Times by an anonymous solid fuel rocket analyst knowledgeable about the SRBs, the article posed O-ring failure as the cause. Further, the article stated that "concerns about the O-rings had been expressed in agency documents at least as far back as 1982." In July 1985, Richard C. Cook, a budget analyst at NASA who assessed the costs associated with the SRBs, wrote a memorandum warning that flight safety was being jeopardized by charring and erosion of the seals. Moreover, a NASA internal memorandum stated that seal erosion had occurred 12 times during flights and contradicted Lovingood's testimony by noting that in one case the secondary O-ring showed erosion also.
In response to the Times story, the Commission held a closed session on February 10. The Commission questioned personnel from Marshall Space Flight Center, the NASA center responsible for the shuttle's entire propulsion system, which included the Orbiter's Main Engine, the External Tank, and the SRB, and Morton Thiokol, the contractor responsible for the SRM (see appendix B, figs. B2.1–B2.5). It began to uncover the true extent of the SRB joint problems, which had not been disclosed by NASA administrators. A dramatic turning point in the inquiry was the Commission's discovery of another critical bit of information that NASA top officials had failed to mention: during the teleconference, Morton Thiokol had initially recommended against the launch. The Commission immediately shifted its inquiry to the O-rings as the probable cause, probing extensively into the history of the O-ring problem and the midnight-hour teleconference. Two additional closed sessions were held, which included NASA and contractor participants in the teleconference on the eve of the launch. Subsequently, the Commission issued a statement that the decision-making process may have been flawed, requesting that no person involved in that process participate in the NASA internal investigation. The Commission's stance toward NASA thus shifted from cooperative oversight to confrontation.
In June 1986, the Commission's report to the President identified the O-rings as the technical cause of the tragedy. Analysis of flight data, films, and the debris of the Challenger retrieved from the ocean floor indicated that the O-rings in the aft field joint of the right SRB did not do their job. Designed to seal the gap created by pressure at ignition, the O-rings' resiliency was impaired by the unprecedented cold temperature on the morning of the launch. Moreover, the zinc chromate putty designed to insulate the O-rings from hot combustion gases failed. Upon ignition, hot propellant gases penetrated the putty. Instantaneously, the gases moved through the putty-filled 3.25"-long, 0.25"-wide seam between segments of the SRB, impinging on the O-rings. O-rings, grease, and joint insulation began to burn. For a few seconds, the charred matter from burned material clogged the gap between the tang and clevis, preventing a launch pad debacle and allowing Challenger to begin its ascent.
Excerpted from The Challenger Launch Decision by Diane Vaughan. Copyright © 1996 The University of Chicago. Excerpted by permission of The University of Chicago Press.
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