Who says we need to move off of this planet and on to another? See the Stanford Torus[1]. We could live in stations such as that and hop down to planets to min

Who says we need to move off of this planet and on to another? See the Stanford Torus[1]. We could live in stations such as that and hop down to planets to mine new materials (or from asteroid mining) when we had to. The entire world's population could fit in about 30,000 of those stations (assuming it's designed for 140,000 people). Having the human race distributed across 30,000 stations scattered around the solar system / galaxy would certainly make the race more robust to mass extinction events. [1] http://en.wikipedia.org/wiki/Stanford_torus http://en.wikipedia.org/wiki/Stanford_torus