Yes, we are talking about permanent, Earth-independent settlement in space. I didn't mean to imply that the settlements in the man-made structures would be Eart

Yes, we are talking about permanent, Earth-independent settlement in space. I didn't mean to imply that the settlements in the man-made structures would be Earth-dependent. Atmosphere is possible in man-made structures. Gravity can be simulated in man-made structures. I don't believe water is particularly scarce, and it is reusable except for when it's used to create fuel. With the Sun + plants a lot can be done. Mars, on the other hand, has low gravity and is far away from the Sun.