The first settlers are all very well, but a handful of astronauts doth not a colony make. In order to establish a fully-functioning, self-sustaining society on another planet, you're going to need a wide range of skills represented to take care of everything from farming to mining to bureaucracy. Elon Musk, CEO of the space transportation company SpaceX, reckons that about a million people should do the trick. If this estimate is about right, that seems like one hell of a task, but it might not be as insurmountable as it seems at the moment. Of course, we probably aren't going to be able to send them all over at once. If we compare the colonisation of Mars to the European colonisation of the Americas (ethical implications aside for a second), people will go in dribs and drabs, perhaps over the course of the entire 21st and 22nd Centuries. Say that Mars and the Earth come into the optimum alignment every two years or so, we could potentially establish something of a shuttle service to Mars. Although, this wouldn't be a like a week in Centre Parcs, this would be a sell-all-your-stuff-and-move-to-Mars scenario. As with virtually all things, the process would begin with the early adopters, the pioneers, but as more and more people went, more and more people would want and be able to as both the price and risk came down. Just imagine the excitement that would stir up every time there was a new "first" - first settlers, first community, first lab, first farm, first town, first ... pizza place? Perhaps even first birth and first death. With a steady stream of news and images coming back from the brand new Brave New World, the initial challenge of finding a million people willing and able to go to Mars is a distant memory.
