When Elon Musk founded SpaceX (which is currently one of the most valuable private companies in the world), he did so with the dream of setting up colonies on Mars. A lofty goal, mostly because we've ...

O’Neill made his space colony idea profitable by having them build solar power satellites. Huge solar arrays would be deployed in space, collect solar power 24 hours a day and then beam it to Earth.

SpaceX CEO Elon Musk announced Sunday that his company had “shifted focus” from taking humans to Mars to building a ...