Before that: Project Orion would have carried a crew of 150 to the Moon, Mars, and the rest of the solar system - bigger ships would carry crews of thousand to the stars.
Design and concept for nuclear explosion propelled vehicle. Launched from ground on conventions rockets. Concept, design and model built. System worked. Larger the better. Small 10,000 ton vehicle with crew of 150 planed. Would cost same or less than Apollo. 40 million ton (= 265 supersized oil ships) interstellar vehicle next.
Motto: Mars by 1965, Saturn by 1970
Killed in 1964 due to massive political will failure. Reasons: Government inter-agency infighting, NASA Apollo conflict, perceived treaty obligations, lack of political leadership. “...the first time in modern history that a major expansion of human technology has been suppressed for political reasons.” - Freeman Dyson.
It would be better to build it in orbit.🤔