It's a case of the advertising art anticipating life.
In 1952, Wernher von Braun worked out a Mars mission of 963 days that provided sufficient lift capacity to land men on the planet and return them safely to earth. The flotilla he envisioned for the flight to Mars was only slightly smaller than the thousand-plane raids the Army Air Force was staging a few years previously.
Space colonization, however, does not require a round trip.
Establishing a human colony on Mars could go a lot faster if space travelers adopted the same mindset as early American settlers and expected never to return home, two scientists believe.That's a suggestion. Remember, friend, there's no return is being considered by NASA, but it's not yet policy.