On 27 January 1986 Morton Thiokol engineers recommended against launching Challenger below 53 degrees F because the booster O-rings had not been shown to seal…
A 1977 hydroburst test found the tang and clevis bending apart instead of together. Marshall engineers later called the design completely unacceptable.
After the second shuttle flight, inspection found the first in-flight erosion of a primary O-ring. It was not carried into the readiness reviews.
With O-rings at 53 degrees F, 51-C had the worst blow-by so far. Thiokol later made 53 degrees its recommended limit.
Roger Boisjoly wrote that a field-joint failure would be a catastrophe of the highest order, with loss of human life.
Vice president Robert Lund presented the engineering recommendation: no launch with O-rings below 53 degrees F. Kilminster said he could not recommend launch.
In a 30-minute private caucus Thiokol management asked Lund to put on his management hat. Boisjoly said he was never polled.
Thiokol said the data were inconclusive and recommended launch; Kilminster faxed it at about 11:45 p.m. The commission found the final decision-makers did not know of th…
Smoke came from the right booster joint at 0.678 seconds. A flame appeared at 58.788 seconds and the vehicle broke apart at 73 seconds. All seven crew died.
Richard Feynman clamped a piece of O-ring rubber and dipped it in ice water to show it lost resilience in the cold.
A joint design too sensitive to temperature, and a launch decision made without the engineers' objection. It urged a redesign and an independent safety office.
Discovery flew the first mission after Challenger with a redesigned joint that added a capture feature, an extra O-ring and heaters.
Read the complete story, FAQs and key facts.