Krafft Ehricke

Krafft Ehricke was a German-American rocket engineer who co-designed the Centaur, the world's first rocket upper stage to use the high-performance combination of liquid hydrogen and liquid oxygen propellant, a technology that became standard for many later American launch vehicles carrying heavy or high-energy payloads. He trained in aeronautical engineering in Berlin before working on V-2 rocket propulsion at Peenemunde during the Second World War, and after being brought to the United States under Operation Paperclip in 1947 he worked briefly with Wernher von Braun's team before moving to Bell Aircraft and then to Convair, where from 1954 he led development of the Centaur stage alongside contributions to early space station concepts and the nuclear-pulse propulsion study known as Project Orion. Beyond hardware design he wrote extensively on astrodynamics and was an early and influential advocate of gravity-assist trajectories for exploring the outer Solar System, and he developed a philosophical framework he called the Extraterrestrial Imperative, arguing that expanding into space was necessary for the long-term survival and development of humanity. He died in 1984.