In 2017, Elon Musk laid out plans to build a permanent colony on Mars -- one with at least a million human inhabitants. What would this colony look like? How would it work? Most importantly, could we use a Martian colony as an opportunity to improve on the socioeconomic practices of Earth? To find these answers, Ben, Matt and Noel went to the smartest guy they know: Marshall Brain, the founder of HowStuffWorks and author of "Imagining Elon Musk's Million-Person Mars Colony."