This artist's concept from 1962 show a three hundred-sixty ton spaceship, powered by a forty-megawatt nuclear-electric power plant, transporting a three-man crew to Mars. As envisioned by Marshall Space Flight Center engineers, a five-ship convoy would make the round trip journey in about five hundred days.
March 17, 2018 Subject:
Dr. Ernst Stuhlinger
Dr. Ernst Stuhlinger was a member of the von Braun Team going back to their days at Peenemunde. Dr. Stuhlinger had a fascination with electric propulsion for future human missions BEO. - "Stuhlinger and King then described their plan for an ion-drive Mars expedition. They did not offer an expedition start date, though they did say that it would take place in the early 1980s, about 20 years after their presentation. Large Saturn-class or enormous "post-Saturn"-class chemical rockets would launch "modular subassemblies" into LEO, where assembly crews would bolt them together. The expedition would comprise five 150-meter-wide nuclear-powered ion-drive spacecraft of two types. Three "A"-type ships would carry one 70-ton Mars lander each (image at top of post). Two "B"-type ships would lack landers. Each of the five vessels would carry three astronauts on board. The expedition could continue as planned if as many as two ships were lost, provided that they were not of the same type. In an emergency, one ship could return the entire 15-man expedition complement to Earth "under crowded conditions." - https://www.wired.com/2012/04/ernsts-ions-part-3-twirling-ion-mars-ships-1962/