On Sunday Elon Musk said that SpaceX is prioritizing the establishment of a “self-growing city” on the moon over and above his long stated ambition to settle Mars. In a post on his social media ...

SpaceX employees are working on designs for a Martian city, including dome habitats and spacesuits, and researching whether humans can procreate off Earth. Mr. Musk has volunteered his sperm. Credit..