Devon Island is a bleak, windswept wasteland in the Canadian Arctic. It’s as close as you can get to Mars without leaving Earth, and that’s the lure for a band of space-suited “colonists” who are gathering there this week. During a two-month simulated mission to the Red Planet, the Mars enthusiasts will live inside a cylindrical fiberglass “habitat,” and they’ll send dispatches to mission control in Lakewood, Colo. They will trudge across the alien landscape in helmeted canvas spacesuits with back packs, gloves and rubberized military cold-weather boots. And they will be guarded by an Inuit native with a rifle who will watch for polar bears from an ATV.