Liquid water is an essential prerequisite to life as we know it. McKay and his colleagues found one region of Chile’s Atacama so dry that absolutely nothing grows — a discovery, as often occurs in science, made purely by chance.
“We put our meteorological station in the middle of this desiccated zone only because people at the local university told us it was the safest place to leave our equipment where it would not be stolen,” McKay says.
The Very Large Telescope (VLT), one of the world’s premier observatories, is just 50 miles from the research site. If McKay’s astrophysics career had taken a more conventional turn, he might have found himself atop Cerro Paranal, where the VLT is, rather than 5,000 feet below, scouring the desert for hints of life. The pursuit he’s chosen brings to mind a question raised by Victor Hugo in Les Misérables: “Where the telescope ends, the microscope begins. Which of the two has the grander view?” In astrobiology, McKay maintains, the combined view can be especially powerful.
At the moment, some of his collaborators are hard at work in the Atacama, trying to determine the precise edge of the desert’s habitable zone, a tough challenge because organisms there may grow during just one or two damp days a year. “If we can find life’s cutoff on Earth,” McKay says, “that could tell us something useful about what the limit on Mars might be.”