We just passed the 27th anniversary of the fatal explosion of the space shuttle Challenger. The problem that caused the disaster is commonly thought of as an error in polymer engineering. I don’t think of it that way. To me, it was an error of management to an extent that was close to criminal.
I don’t know how much of the information rattling around in my head is on the public record, or how much I just picked up over dinner and from other conversations with plastics engineers and corporate executives of companies like DuPont, which supplied the Viton fluroelastomer in the O-rings used to seal the solid rocket booster (SBR) joint in the Challenger.
After the O-ring failed, hot gas under pressure escaped, starting a sequence of events that led to the complete disintegration of the Challenger, and the death of its seven crew members.
The president of DuPont’s polymers division told me soon after the accident that it was well known and part of Viton’s test data that it was not specified for use at low temperatures. Elastomeric sealing forces decay rapidly as temperatures decrease. Challenger was only certified to launch at 40ºF. It had dropped to 18ºF the night before the launch of Jan. 28, 1986.
Engineers at Thiokol were well aware of the material’s limitations, and opposed a launch. They were overruled by mangers at NASA, and later by their own management at Thiokol.
In a follow-up investigation, Richard Feynman, a physicist who assisted in the development of the atomic bomb, was extremely critical of NASA management. He said that NASA’s estimates of reliability differed as much as a thousandfold from the estimates of working engineers.
A later U.S. House investigation later tried to shift the blame back to poor technical decision-making by NASA and contractor officials. Edward Tufte, an expert on visual communications who was hired to look at the communications issues involved, also tried to shift blame back to Thiokol engineers for failure to adequately communicate the risks involved. Tufte is an entertaining presenter, but his technical acumen came under severe attack.
Funny thing. NASA postponed flights at the drop of a hat if the weather was at all cloudy. But even the possibility–even what may have been thought of as a remote possibility–of an extreme safety risk involving O-rings? No postponement.
It was a tragedy, and someone really should have gone to jail for criminal negligence.