First nuclear submarines, now a nuclear helicopter — but powered by slightly different principles. Daedalus has designed a free-flying helicopter rotor with blades that have a radioactive coating on one side. Nuclear decay will keep these surfaces warm, causing impinging air molecules to rebound with added momentum and spin the rotor. Such a helicopter would fly indefinitely at a safe height and, from there, it could even be used to repair the ozone layer, because nuclear radiation can convert oxygen to ozone much more efficiently than solar ultraviolet light.