As hard as it might be to believe, the tragedy of the space shuttle Challenger explosion is nearing its thirty-fifth anniversary. While honoring the somber occasion, risk communicators can note an important lesson about visuals from Professor Edward Tufte.
A leading expert on the use of visuals in risk, high-concern, and crisis communication, Professor Edward Tufte of Yale University makes a strong case for the importance of visuals in high-stress communication in his discussion of the Challenger accident.
In 1986, the space shuttle Challenger exploded, killing all seven crew members. The crew consisted of five NASA astronauts, one payload specialist, and a civilian school teacher.
The immediate cause of the accident was the failure of the O-rings, due largely to unprecedented low temperatures. Rubber O-rings are meant to seal in flammable fuel and vapors at ignition.
The O-rings leaked, and the fuel and vapors caught fire. The flames reached the solid rocket booster, and then the external tank containing liquid hydrogen and oxygen.
The result was a horrendous explosion 73 seconds after takeoff. The explosion was viewed by millions, including school children around the world.
The O-rings had lost their resiliency because the shuttle was launched on an unusually cold day in Cape Canaveral, Florida. Temperatures on the day of the launch were in the low 30s, and the O-rings themselves were colder, less than 32°F.
On the day before the flight, the predicted temperature for the launch day was 26°F to 29°F. Concerned that the rings would not seal at such cold temperatures, engineers involved in designing the rocket expressed statistical concerns.
Their concerns came from several sources, including statistics describing the history of O-ring damage during previous cool-weather launches of the shuttle, the physics of O-ring resiliency (which declines exponentially with cooling), and experimental data.
The statistical evidence describing the potential for O-ring failure was sent to the National Aeronautical and Space Administration (NASA), the government agency responsible for the flight NASA engineers, and officials noted serious weaknesses in the numbers and statistics and determined that the numbers and statistics were inconclusive.
Discussions among officials and engineers lasted well into the night. The decision was made to go ahead with the launch. On the morning of January 28, 1986, the rocket exploded soon after the launch, killing all aboard.
Did It Have to Happen?
Since the catastrophe, scholars and commentators have debated about what happened and whether the tragedy could have been prevented. For example, why were multiple warning signals and statistics ignored about the risk of low temperatures damaging the O-ring seals?
American sociologist Diane Vaughan proposed a cultural theory of risk explanation. She argued the Challenger tragedy was “a mistake embedded in the banality of organizational life and facilitated by an environment of scarcity and competition, elite bargaining, uncertain technology, incrementalism, patterns of information, routinization, organizational and interorganizational structures, and a complex culture.”
The following are some of the many explanations cited by the Report of the Presidential Commission on the Space Shuttle Challenger Accident:
• incomplete statistical analysis by engineers
• violation of safety rules
• “group think”—a worldview preference for consensus as opposed to independent thinking
• deadlines and a tight project schedule
• pressure to conform to bureaucratic norms and decision-making processes (don’t talk back once a decision has been made by a higher-up)
• pressure to have a successful launch
• organizational values that encouraged risk-taking
In the aftermath of the tragedy, many questions arose:
Was the decision-making and risk-communication process distorted by “group think”?
Were the NASA and contract engineers and officials feeling pressure to have a successful launch following the extensive publicity campaign surrounding the launch, including having a schoolteacher on board and encouraging schools to take a break from classes to watch the launch?
Were the statistics too complex for nonexpert risk managers and decision makers to understand?
Were political factors at play that argued against delay of the already delayed launch?
How Could Visuals Have Helped?
In his book Visual Explanations, Tufte raised another question: Could the risk numbers and statistics have been communicated more effectively using visual communication tools to convince risk managers and decision makers to delay the launch?
The book discussed in detail the use of visual evidence in deciding to launch the space shuttle Challenger. Tufte reproduces many of the statistics presented to NASA officials. The numbers and statistics are extremely dense and complicated, including complex statistical explanations of the physics associated with the resiliency of the O-rings.
Tufte took the data the engineers presented to officials and put it into a single visual chart. He argued this visual could have changed history. He reduced the large number of statistical questions down to one question: What is the correlation between temperature and damage to the O-rings?
He produced a chart that plotted all the shuttle launches with temperature at launch on one axis and with a “damage index” on the other axis. The chart showed there were several instances of damage occurring at warm temperatures. However, every launch colder than 65° had some damage.
Furthermore, the visual showed damage increased as the temperature got colder.
The coldest launch before Challenger was at 52°. The Challenger rocket was launched when the temperature was in the mid to high 20s.The three key messages of the visual were
1. Every launch colder than 65° had O-ring damage.
2. Damage got worse as it got colder.
3. Expected temperatures on the launch date were significantly colder than other launches.
In this case, a well-executed visual may have communicated more information, more quickly and clearly, than the dense and complicated statistical presentation, allowing a different decision that may have changed history.
More about Visuals
In his book Visual Explanations, Tufte described strategies for the arrangement in space and time of images, words, and numbers.
Visuals include graphs, charts, animation, photographs, maps, and pictures.
Visual information is typically processed faster than verbal information. Well-designed and presented visuals are an effective means in high-stress situations to increase audience attention, understanding, and recall.
Communicating Effectively When Feelings, Fears, and Facts Collide
More information about visuals and risk communication can be found in Dr. Covello’s video-based course Pathway to Risk, High-Concern, and Crisis Communication. This master class introduces communicators to the tools and techniques for communicating effectively—while providing greater insight into why audiences react the way they do during times of stress.
The course comprises nine video lectures and accompanying text modules, plus supplemental materials for putting valuable lessons into practice.
More information about the course, including group rates and partnering opportunities, can be found by emailing firstname.lastname@example.org.
Dr. Vincent Covello
Dr. Vincent Covello, director of the Center for Risk Communication, is one of the world’s leading experts and practitioners on risk, high-concern, and crisis communication. He is the author of more than 150 articles in scientific journals and the author/editor of more than 20 books. Dr. Covello is a consultant, writer, and teacher. He is a frequent keynote speaker and has conducted communication skills training for thousands.
Vaughan, D. (1996). The Challenger Launch Decision. Chicago: University of Chicago Press. p. xiv.
Presidential Commission on the Space Shuttle Challenger Accident (1986). Report of the Presidential Commission on the Space Shuttle Challenger Accident. Washington, DC: Presidential Commission on the Space Shuttle Challenger Accident. See also: Vaughan, D. (1996). The Challenger Launch Decision. Chicago: University of Chicago Press; Dalal, S.R., Fowlkes, E.B., Hoadley, B. (1989). Risk Analysis of the Space Shuttle: Pre-Challenger Prediction of Failure. Journal of the American Statistical Association, Issue 84, no. 408 (December 1989): 945–957; Esser, J.K.,Lindoerfer, J.S (1989). Groupthink and the Space Shuttle Challenger Accident: Toward a Quantitative Case Analysis. Journal of Behavioral Decision Making. Issue 2, no. 3, 167–177.
Tufte, E. (1998). Visual Explanations (Third Edition). Cheshire, CT: Graphics Press.