January 28th, 1986 was especially chilly for Cape Canaveral, Florida, where the average low in January is 8 °C. That morning the mercury had dipped to -2°C. In a teleconference the afternoon before the launch, the engineers from Morton Thiokol, manufacturers of the Challenger's solid rocket booster, argued that the launch should be delayed. They did not have enough data to predict how the rocket-motor seal would work in low-temperature conditions.
Each of the shuttle’s two solid rocket boosters was made up of four sections, each of which was held together by a tang on one section that fit into a coupler on the other. A rubber O-ring and putty made of zinc chromate filled with asbestos formed a seal at the join. A second ring acted as a backup. When the solid rocket boosters fired the combustion of the propellant would produce tremendous heat and pressure.
At the same time, the million pounds of thrust from the liquid-fuel rockets would create enormous forces and bend the solid rocket boosters slightly. Only the O-ring would keep hot gases from blowing out of the seal. The Challenger had been sitting on its launching pad for 38 days prior to launch. During that time, 17.8 cm (7 in.) of rain had come down. No one was sure how these conditions would affect the rings.
In the end the decision was made to launch anyway, with disastrous consequences. Cold weather combined with a defect in the solid rocket booster were to blame for the astronauts’ deaths.
Learn how the weather has effected many historical events!
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