The National Aeronautics and Space Administration was preparing the space shuttle Challenger for launch on the morning of Jan. 28, 1986. It was an unusually cold morning for Cape Canaveral, Fla.—too cold, warned the engineers of NASA contractor Morton Thiokol, builder of the shuttle’s solid rocket motors. The day before the launch, Thiokol engineers and executives met with NASA officials on a teleconference. A Thiokol engineer reported the anticipated temperature during the following day’s launch time would be around 26 degrees. Erring on the side of caution, Boisjoly, Thompson and other engineers recommended delaying the launch.

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