Question: In what year did the inventor of the mass driver propose a design for a space settlement?
Sentence (from "The High Frontier: Human Colonies in Space"): It envisions large manned habitats in the Earth-Moon system, especially near stable Lagrangian points. Three designs are proposed: Island one (a modified Bernal sphere), Island two (a Stanford torus), and Island 3, two O'Neill cylinders.
Relevant evidence: No