Making Humans a Multi-Planetary Species Google 8 years ago Really simple read (in principal) http://online.liebertpub.com/doi/pdf/10.1089/space.2017.29009.emu http://bigthink.com/paul-ratner/elon-musk-releases-plans-for-colonizing-mars-and-other-planets Share this: Click to share on X (Opens in new window) X Click to share on Facebook (Opens in new window) Facebook