The recent discovery of abundant water on Mars, albeit in the form of permafrost, has raised hopes for finding traces of life there. The Red Planet has long been a favorite location for those speculating about extraterrestrial life, especially since the 1890s, when H. G. Wells wrote The War of the Worlds and the American astronomer Percival Lowell claimed that he could see artificial canals etched into the planet’s parched surface. Today, of course, scientists expect to find no more than simple bacteria dwelling deep underground, if even that. Still, the discovery of just a single bacterium somewhere beyond Earth would force us to revise our understanding of who we are and where we fit into the cosmic scheme of things, throwing us into a deep spiritual identity crisis that would be every bit as dramatic as the one Copernicus brought about in the early 1500s, when he asserted that Earth was not at the center of the universe.