Orion Nuclear Pulse Rocket

This model at the Smithsonian Steven F. Udvar-Hazy Center represents one of the most famous concepts for spacecraft propulsion: Project Orion.  In the 1950s, scientists proposed detonating nuclear bombs behind a spacecraft.  The pulse from the explosion would hit a pusher plate (imagine a giant version of the buffers on British/European railroad cars), and send the spacecraft flying forward at high speed.  Freeman Dyson proposed using Orion-type spacecraft, which could reach 10% of the speed of light, for interplanetary and interstellar missions, including the colonization of space.  However, Project Orion was cancelled, as the Partial Test Ban Treaty of 1963 restricted the use of nuclear devices, and the government decided to look into alternative propulsion systems.  The "Orion drive" has since gone on to find a new life in science fiction.