Some believe that the planet Mars holds promise as a new home for humankind and that it could become the focus of a large scale colonisation effort at some undefined point in the future. In this paper I support the assertion that Mars holds promise as a site for human scientific, and possibly commercial, exploration, but I question the idea that Mars will be colonised in a manner akin to the New World. The surface of Mars is physically extreme. Mean annual temperature is -60 C, the ultraviolet radiation flux is a thousand times more damaging to DNA than that found on the surface of the earth, and there is little or no liquid surface water. The atmosphere is unbreathable and the soil may be toxic. Although Mars is less awful than the most awful places in the solar system (such as the radiation bombarded surfaces of the Jovian moons), it is considerably more awful than the most extreme places on earth, such as the continental interior of Antarctica and the High Arctic. I suggest that the polar model of human settlement is the most accurate from which to extrapolate the future of human Mars exploration, but even this model is optimistic. Using the most hopeful assessments of colonisation prospects, the human population of Mars would be a maximum of about three million people, and would most probably be substantially less. Understanding the most likely social trajectory of human Mars exploration is not only sociologically interesting, but it is practically, important for determining how Mars exploration programmes should be presented to the public.