Astrobiologist Chris McKay travels to the world’s harshest landscapes to search for clues about the potential for life on other planets. He’s endured clouds of mosquitoes in the Siberian permafrost and prepared for polar bear attacks in the Canadian Arctic.
McKay calls his favorite field sites — picked for both scientific and aesthetic reasons — the “seven wonders of the Mars analog world.” But his search to understand possible alien ecosystems isn’t limited to the Red Planet. His research trips have taken him to Saturn’s moons and the volcanoes of Venus — or at least, as close as he can get without leaving terra firma.
1 – The Namib Desert, Namibia, Africa
The Namib in southern Africa is one of the world’s foggiest deserts, and fog is the main source of moisture for its western region. Fog’s important role in sustaining microbial life drew McKay to the southern African desert, but the Namib also features some of the world’s tallest sand dunes, rising as high as 1,000 feet. These dunes are linear, or longitudinal, formed when winds blow in two predominant directions, varying seasonally — like the dunes on Titan, Saturn’s largest moon.
2 – Ol Doinyo Lengai, Tanzania, Arfica
The Tanzanian peak looks like a classic conical volcano from a distance. But instead of the red-hot lava we associate with volcanoes, what pours out of Ol Doinyo Lengai looks more like motor oil. It’s the only active volcano in the world that spews “carbonatite” lava, composed primarily of carbonate minerals rather than more common basalt lava.
Studies of Ol Doinyo Lengai and its unusual lava may help solve a puzzle related to Venus, which has more than 1,000 volcanoes and a surface riddled with about 200 lava channels.
3 – Atacama Desert, Chile, South America
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.
“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.”
4 – Lake Untersee, Antarctica
In 2008, McKay and his colleagues drilled through the ice covering Antarctica’s Lake Untersee and dove in, discovering colored mounds of bacteria on the lake’s floor unlike anything seen before. Untersee is a good model for Mars, he says, because it is supplied by subglacial melt — water that accumulates at the bottom of an ice pile — rather than from surface melting, which does not occur on Mars.
5 – Iceland’s Great Geysir, Iceland
This attraction for tourists and astrobiologists alike sporadically shoots steaming water from an underground hot spring 200 feet into the air.
Geyser activity has been seen on other worlds as well. The Voyager 2 spacecraft discovered four active geysers on Triton, Neptune’s largest moon. And images captured by the Cassini spacecraft revealed a gigantic plume emanating from a geyser on Saturn’s moon, Enceladus, which sends ice, water vapor and other chemicals thousands of miles into space.
6 – Pico de Orizaba, Mexico, North America
Visible from the Gulf of Mexico and rising about 18,500 feet above sea level, this snowcapped volcanic cone is the highest mountain in Mexico. McKay has visited the peak of Pico de Orizaba a dozen times to study the mountain’s tree line, which is the world’s highest.
Here, pine trees grow at elevations above 13,000 feet. If Mars turns out to be devoid of life, McKay advocates “terraforming” it — altering its climate and atmosphere to make it suitable for Earth-like life. “If you want to get serious about life on Mars, you want to make trees,” which he says are important for producing oxygen on massive scales.
7 – Lake Vostok, Antarctica
Buried under a sheet of ice 2.5 miles thick, Lake Vostok is the world’s seventh-largest freshwater lake and the largest of more than 300 lakes trapped beneath the Antarctic ice sheet. Its water may have been isolated for more than 15 million years. Although he’s written research papers about the lake, McKay has never been there. No human has, but human technology — in the form of a drill operated by Russian scientists — reached Vostok in 2012.
Scientists analyzing samples of the lake’s waters have not yet released conclusive findings about possible microbial life, but discovering an ecosystem in Vostok would hearten McKay, who wonders whether a subsurface ocean of Jupiter’s moon Europa, which is covered with about six miles of ice, might similarly harbor life.