January 28, 1986 – Explosion of the Space Shuttle Challenger

On January 28, 1986, the space shuttle Challenger broke apart 73 seconds into its flight, leading to the deaths of its seven crew members.

Crew of the Challenger

Crew of the Challenger

A few days after the explosion of the Challenger, physicist Richard Feynman was asked by the head of NASA to be on a presidential commission investigating the accident. (Richard Feynman, the late Caltech physicist, was a Nobel Prize winner in physics.)

Feynman, in one of his several autobiographical books, What Do You Care What Other People Think?, describes what happened to the Challenger in detail, based on what he learned during the investigation. Members of the commission received many briefs on all the parts of the shuttle and how they fit together. There was a lot of information, and it was technical and confusing.

p14-88

Then in a closed meeting of the commission, an engineer from Thiokol Company, Mr. McDonald came to testify, on his own, uninvited. He told the surprised members that Thiokol engineers had been concerned about the effect of low temperatures on the O-ring seals between the rocket joints. The rubber of the O-rings had to be resilient in order to expand and make the seal. Thiokol engineers had indicated to NASA that the shuttle shouldn’t fly if the temperature fell below 53 degrees. Engineers and managers at NASA however, were not convinced by the evidence presented by Thiokol. On the morning of January 28, the temperature was 29.

The next day following the closed meeting, an open, televised meeting was scheduled. Feynman started his morning with a trip to the hardware store and got some tools. As the meeting convened, he asked for ice water. He took some O-ring pieces he had in his pocket, squeezed them in a C-clamp, and put them into the glass of ice water. He pressed the button for the microphone, and announced the results of his experiment: “I discovered that when you undo the clamp, the rubber doesn’t spring back. In other words, for more than a few seconds, there is no resilience in this particular material when it is at a temperature of 32 degrees. I believe that has some significance for our problem.”

feynman_icedunk

As Feynman reported, “…that night, all the news shows caught on to the significance of the experiment, and the next day, the newspaper articles explained everything perfectly.”

Feynman concluded his testimony by stating: “For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.”

Edward R. Tufte has also written about the Challenger disaster in his book Visual Explanations: Images and Quantities, Evidence and Narrative, in which he argues that it was the poor presentation of evidence by Thiokol engineers that beclouded the message they were trying to send. NASA employees could not detect the danger from the confusing graphics prepared by Thiokol. Tufte, also the author of The Visual Design of Quantitative Information, and Envisioning Information, demonstrates graphically how careful design of information can have an effect on the efficacy of communication.

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