Read George Dyson’s (Freeman’s son) book ‘Project Orion: The Atomic Spaceship 1957 – 1965’ for a fascinating overview of the entire project.

The 10,000 ton version would have done a 3 year round trip to one of Saturn’s moons, Enceladus, delivering a 1,300 ton payload and originally planned to happen in 1970. The ‘Advanced Interplanetary Ship’, as it would be called, would have 4G acceleration using 15 kiloton ‘propulsion modules’