NASA-project-orion-artist. NASA public domain image colelction.

An artist's conception of Project ORION; from NASA. This picture shows NASA's reduced-size 6,000 ton version of the small-sized Project Orion craft. Three sizes were originally specified, from 10,000 to 8 million tons in Project Orion's initial report. The model shown can take off from Earth, and explore Saturn (shown in the background), refuel (with water for reaction mass) and return with a manned crew using a single-stage in fourteen months. The artist's depiction shows the craft about 4 milliseconds after the explosion of a nuclear propellant charge. The glow around the base of the craft is the ultraviolet-glowing plasma from the explosive recompressing against the pusher plate. The shock absorbers have not yet compressed. There are two shock absorbers: the doughnut near the plate, and the long tubes between the doughnuts and the capsule. The propellant charges and handling machinery are between the shock absorbers and the crew cabin. The two tubes on either side of the crew cabin are companionways. The pusher plate is approximately a meter thick, made of steel, and effectively shields the craft from radiation. Oil is sprayed on it on before each cycle to prevent ablation. The explosives are nuclear shaped charges ejected by a gas gun through the pusher plate. This design has about one one-kiloton explosion per second when under thrust. The specific impulse is (conservatively) 2,000 seconds. The craft can be made from steel, using construction techniques similar to those of submarines. Project ORION craft are not in use because poisonous fallout is created by the known designs for nuclear explosives.