Is the exploration of space justified by our natural wanderlust? Are we morally obliged to terraform other planets in order to avert stagnation or extinction on Earth? Should we worry about the socio-economic consequences of asteroid mining, or the aesthetic damage done by the extraction of Helium-3 from the moon?

Mars has been a wandering star, a vengeful God, and latterly a storied world of shifting greenery, huge canals, carved faces, pyramids, aliens, and warrior princesses. Today, it is hard to see Mars through the haze of these cultural-historical associations. In the midst of this haze, it seems quite reasonable to talk about terraforming. If…

(Review for the Astrobiology Society of Britain.) In Lucky Planet, David Waltham argues that Earth’s teeming, complex biosphere is a rare anomaly in an almost sterile cosmos. From the start, he acknowledges that many of us have strong intuitions to the contrary: isn’t Earth just another planet orbiting just another star? There are trillions of…