Let’s say you’re in charge of a Mars mission. Okay boss, where do we land? The total surface area of Mars is roughly equal to the land area of Earth. Nobody’s ever built a settlement there (heck, nobody’s even gone there). It’s free and wild and open territory. Yeah, there might be some legal issues surrounding international laws and outer space treaties, but we’ll let the folks back home deal with that. You’re in charge, and you have to pick a spot to plant down roots.