IN CASE YOU'VE NEVER CHOSEN to visit North Dakota for a week in the dead of winter, let me assure you that it's really tough to explain why any fully evolved Homo sapiens would. Here, just shy of the Canada border, as you're about to check in to the lonely Golden Hub Motel, in the town of Crosby, all you hear is the squeak of your feet on snow, and no horizon delineates the frosty sky from thousands of acres of frosty fields. Staring at this desolate scene is like being in a very cold cloud, or how I imagine we might greet the white light of death. The question Why are you here? is soon followed by Why? Yes, it's the kind of place that can drive a man to commit philosophy.

Speaking concretely, I'm here to follow the To Cross the Moon (2XtM) expedition, a second attempt by three buddies to traverse the lunar-looking state, powered only by wind. Jason Magness, 32, Sam Salwei, 26, and Paul Cassedy, 19, plan to use snowkites—large parafoils clipped to hip harnesses via 80-foot lines—to tow themselves on skis and snowboards across North Dakota's farms, ranchland, and frozen lakes. Starting in the far northwestern corner, they'll head south to 150-mile-long Lake Sakakawea, cross it, and then glide on down to SoDak. At the same time, a four-person education team will bounce around drumming up popular support for wind farms while a rotating roster of volunteer photographers and videographers (the "media crew") documents it all.

When I catch up with the adventurers on their second day, Paul, a quiet kid who's new to kite-skiing, is seated in a field of snow-dusted wheat stubble, his face hidden behind his helmet, balaclava, rime-covered neoprene mask, and fogged goggles. His mitts are frozen solid, so he paws dumbly at the lines, trying in vain to take flight. Then he finds the center line and pulls it to his chest, the kite inflates with a bang, and he's off! In the wrong direction. Until he falls 50 yards away. Taking a divot out of the snow with his chin.

Nearby, Sam is having a blast. A puckish Crystal, North Dakota, native who's kite-skied hundreds of miles, he swoops his rasta-themed kite directly overhead and launches six feet into the air: "Yoooooo!"

Jason, the group's strongman, seems unfatigued, despite having run 70 miles in an adventure race just four days ago. He yells encouragement to Paul, who once again is in a crumple: "Let's go, Paul! You're only 19! You've got a lot more suffering ahead of you!" Jason then vaults skyward, imitating Sam. Before his skis leave the ground, however, his 50-pound pack tips backwards and turtles him.

Hard to believe, but their plan is to continue this way, self-supported, for 400 miles, in temperatures that will bottom out at minus 42. They will go farther on less food than I imagined possible, and they will tangle a kite high in the branches of the only tree in sight—all without once doubting the tilting-at-windmills brilliance of their mission.