Rather than a base moon or mars or any planet, why not a space colony with pluggable units using a standard plug-in architecture to exchange energy, supplies etc. (Similar to an API). There is no main unit, similar to a P2P structure, and units can be stacked together to make huge colonies. Each cluster of units may move in an upfront known trajectory in the habitable zone of the Sun. The whole idea is that space startups may create newer units based on new ideas; and that way we may explore the space quicker.