Antarctic Dry Valleys

The most extreme, most inhospitable lands on Earth are the McMurdo Dry Valleys, near the coast of Antarctica, just inland from the McMurdo science base.We normally think of Antarctica as covered in ice. But the dry valleys are surrounded by mountains, which block precipitation. What little water does accumulate is blown away by the constant winds.And yet, there is life.From December to March, the Antarctic summer, 24-hour sunshine melts ice in the mountains, producing meltwater streams that trickle into the valleys. They fill shallow, ice-covered lakes, in which microorganisms thrive.When the water evaporates, some of those micro-critters continue to live in brine pools. Others persist in the soil.Others live inside the glaciers that surround the valleys. That’s because trapped within them are the remnants of an ancient ocean. The water is too salty to freeze, and devoid of oxygen.But the microbes metabolize sulfur and iron, which may come from the glaciers scraping over iron-rich rocks as they move.One of the glaciers terminates in the dry valleys, where it secretes its red brine at Blood Falls.Scientists believe this frigid hellscape, blasted by wind and blistering UV rays, is the closest environment on Earth to Mars.So they’re studying it, to learn how life can survive here -- and how it might survive on the Red Planet itself.