Sam Hoffman was an American scientist and engineer known for his work on nuclear propulsion systems. He played a leading role in the development of the nuclear rocket engine under the U.S. government's Project Rover and NERVA programs during the Cold War. He specialized in the design and testing of nuclear thermal rocket engines. Hoffman's work was critical in advancing technology that could enable long-distance space travel, including potential missions to Mars. He collaborated closely with NASA and the Atomic Energy Commission during the height of the U.S. space race.