RICHARD FEYNMAN AND THE CHALLENGER

After the space shuttle Challenger and its crew were destroyed in a fiery explosion in January of 1986, NASA appointed members of the Rogers Commission to investigate the cause of the disaster.
To find out what happened to the shuttle, he went to the people who put the shuttle together. He learned many things from these people that would help him to discover the cause of the explosion; and also information that helped him realize what a risky business flying a shuttle really is. NASA officials said that the chance of failure of the shuttle was about 1 in 100,000; Feynman found that this number was actually closer to 1 in 100. He also learned that rubber used to seal the solid rocket booster joints using O-rings, failed to expand when the temperature was at or below 32 degrees F (0 degrees C). The temperature at the time of the Challenger liftoff was 32 degrees F.
Feynman now believed that he had the solution, but to test it, he dropped a piece of the O-ring material, squeezed with a C-clamp to simulate the actual conditions of the shuttle, into a glass of ice water. Ice, of course, is 32 degrees F. When the material in the SRB (solid rocket booster) starts to heat up, it expands and pushes against the sides of the SRB. If there is an opening in a joint in the SRB, the gas escapes. This leak in the Challenger's SRB was easily visible as a small flicker in a launch photo. This flicker turned into a flame and began heating the fuel tank, which then ruptured. When this happened, the fuel tank released liquid hydrogen into the atmosphere where it exploded.
As Feynman explained, because the O-rings cannot expand in 32 degree weather, the gas finds gaps in the joints, which led to the explosion of the booster and then the shuttle itself.