Feynman showed why the Challenger shuttle failed

Person: Richard Feynman
Lived: 1918–1988
Field: Physics
From: American

The story

On 28 January 1986 the Space Shuttle Challenger broke apart 73 seconds after launch from Cape Canaveral, Florida, killing all seven crew members, among them the schoolteacher Christa McAuliffe. Because of the Teacher in Space project, many schoolchildren across the United States watched the launch live. A presidential commission chaired by William P. Rogers was set up to find out what had gone wrong.

Richard Feynman, then a professor at Caltech who had already undergone surgery for cancer, was reluctant to join, but his wife Gweneth persuaded him. He preferred his own direct methods of investigation to the commission's schedule, talking to engineers and asking simple questions, and he clashed at times with Rogers. A hint from a fellow member, General Kutyna, pointed him towards the effect of cold on the rubber O-rings that sealed the joints of the solid rocket boosters. The temperature on launch morning had been below freezing, far colder than on any previous launch.

During a televised hearing, Feynman compressed a sample of the O-ring material in a clamp and dropped it into a glass of ice water. The simple demonstration showed that the rubber became less resilient in the cold, and so less able to keep a tight seal. The commission concluded that the disaster was caused by the primary O-ring failing to seal properly in unusually cold weather.

Feynman also found a troubling gap between NASA's engineers and its managers. Managers had estimated the chance of losing a shuttle at 1 in 100,000, while engineers he polled anonymously put it between about 1 in 50 and 1 in 200. Feynman insisted that his observations appear in the report, and they were published as Appendix F. In it he warned that for a successful technology, reality must take precedence over public relations, for nature cannot be fooled. He later described the investigation in his 1988 book What Do You Care What Other People Think?

The shuttle fleet was grounded for two years and eight months while the boosters were redesigned. Feynman's demonstration remains one of the most famous moments in the history of engineering safety, a reminder that honest testing and clear communication save lives.