How long is the overarching goal of establishing a self-sustaining Martian city projected to take after the first crewed missions?

Between 20 to 30 years

The vision extends far beyond simply landing humans on Mars; it includes establishing a permanent presence. The text specifies the timeline associated with achieving colonization—the establishment of a self-sustaining city capable of growth. This grand objective, which ultimately aims to host a million people, is projected to require a considerable duration spanning between two decades and thirty years subsequent to the successful completion of the initial crewed missions. This long-term commitment highlights that achieving multiplanetary species status is a multi-decade endeavor predicated upon proving out the foundational transportation and life support systems first.