Project Orion (nuclear propulsion)

Project Orion was a study conducted in the 1950s and 1960s by the United States Air Force, DARPA,^[1] and NASA into the viability of a nuclear pulse spaceship that would be directly propelled by a series of atomic explosions behind the craft.^[2][3] Following preliminary ideas in the 1940s,^[4] and a classified paper co-authored by physicist Stanisław Ulam in 1955,^[5] ARPA agreed to sponsor and fund the program in July 1958.^[6][7]

Early versions of the vehicle were designed for ground launch, but later versions were intended for use only in space. The design effort took place at General Atomics in San Diego,^[5] and supporters included Wernher von Braun,^[8] who issued a white paper advocating the idea.^[2][9] NASA also created a Mars mission profile based on the design, proposing a 125 day round trip carrying eight astronauts with a predicted development cost of $1.5 billion.^[8] Non-nuclear tests were conducted with models, with the most successful test occurring in late 1959,^[7] but the project was ultimately abandoned for reasons including the 1963 Partial Test Ban Treaty,^[10] which prohibited nuclear explosions in space amid concerns over radioactive fallout.^[2]

Physicists Ted Taylor and Freeman Dyson led the project, and Taylor has been described as the "driving force behind Orion."^[6] In 1979, General Dynamics donated a 26 inch (56 cm) tall wooden model of the craft to the Smithsonian, which displays it at the Steven F. Udvar-Hazy Center in Fairfax County, Virginia.^[10]