Visiting other planets is a dream that most of us alive today will have to experience vicariously through probes like the plucky NASA Mars rovers, which have sent a thousand photo albums' worth of snapshots back to Earth. But here's what most people don't realize: you can get a feel for visiting other worlds just by going to certain places on our own planet.

Scientists have sought out these planetary proxies for years, attempting to understand whether life might arise in such desolate environments, and how we would know it if it did. Ellesmere Island, a rocky expanse of glaciers and mountains off the coast of Greenland, bears remarkable similarities to a far-off moon, and it hosts a peculiar kind of bacteria that extracts the oxygen it needs to live from sulfate minerals in surrounding ice. Scientists believe that similar organisms might thrive on Europa, a moon orbiting Jupiter that is thought to have liquid oceans beneath a surface of ice. If Europa is indeed home to such psychrophiles (living things that thrive in extreme cold), studying them here on Earth might make it easier to detect them with NASA probes in the future.