Just 73 seconds after launch on January 28th, 1986, the Challenger space shuttle broke apart over the coast of Florida and ended the lives of all seven crew members. A subsequent investigation determined that an O-ring failure on one of the shuttle’s solid rocket boosters, coupled with extremely cold weather around the time of launch, caused the accident.
6 months prior to the launch, the following memo was sent by Roger Boisjoly — an engineer working at Morton Thiokol, the manufacturers of the solid rocket boosters — to the company’s Vice President, in which he predicted the problem and warned of a potential “catastrophe of the highest order.”
Boisjoly’s warning went unheeded; he then attempted to halt the launch, unsuccessfully. Boisjoly later revealed this memo to the presidential commission investigating the disaster and was then forced to leave Morton Thioklol after been shunned by disgruntled colleagues. In 1988 he was awarded the AAAS Award for Scientific Freedom and Responsibility for his actions.