Wouldn't it make sense to build elysium type habitats orbiting earth before trying to colonize other planets/moons? I mean in terms of maximizing chances of survival for the species. Habitats orbiting earth increase humanity's chances of surviving a cataclysm almost as much as colonizing another planet but in the time it would take for life on Mars to become viable we could build enough habitats to support tens of thousands of people. It's also more convenient because it's closer to earth (communication, repairs, supplies, visits, etc.).