In recent years NASA biologists have identified numerous species of
microbes living on the doorstep to the cosmos: in spacecraft-assembly facilities, on
rovers, orbiters, and circuit boards, and aboard the International Space Station. Some
species are commonplace; others are entirely new and have adapted to—and perhaps
even evolved in—the harsh conditions that NASA decontaminators have devised
expressly to eliminate them. Now they’re off to Mars, Saturn, and Europa. Almost
certainly a few are already there, alive, quietly waiting for their tiny moment in the sun.