Mars planners are increasingly treating ice not just as a resource to drink or split for rocket fuel, but as a structural material that could shape the first real neighborhoods on another world.

Elon Musk recently announced that SpaceX is putting Mars colonization on the back burner. Instead, he plans to build a cosmic city much closer to home.

Elon Musk is putting his dreams of colonizing Mars on hold and said his SpaceX rocket company will instead focus on building a city on the moon.