John retired as the Chief Scientist for the US Air Force Space Command in 1999. From 1968 to 1981, Darrah served as the senior scientist at the Air Force Weapons Laboratory. Here he studied nuclear weapon design, in particular how to strengthen American weapons against the electromagnetic pulse of a nuclear bomb. The U.S. Armed Forces are better equipped to fight in a nuclear battle as a result of Darrah’s work. In 2015, he was awarded an Honorary Doctors of Science Award by the University of Colorado.