Only the hardiest organisms can thrive in one of the coldest springs on earth. That’s why in the summers of 2017 and 2019, Lyle Whyte took a helicopter to Lost Hammer Spring in the unpopulated High Arctic region of Nunavut, Canada. Snow, ice, salt tufa, rocks, and permafrost surround the unassuming spring, which is nestled among nearly barren, treeless mountains on the island of Axel Heiberg, a few hundred miles from the North Pole. He had traveled to this out-of-this-world place to study the microbes that live in its salty, icy, low-oxygen water in hopes of learning about what life might have been like if it ever emerged in similar spots—on Mars.
In a new paper in The International Society for Microbial Ecology Journal, Whyte and his colleagues write that the microorganisms that live a few inches down in the spring’s sediment can indeed survive the harsh environment. Most Earth species depend either directly or indirectly on solar energy. But these microbes can survive on a chemical energy source: They eat and breathe inorganic compounds like methane and hydrogen sulfide, which makes the area smell like rotten eggs, even from a distance. (The research team’s pilot calls the site the “stinky springs.”) “You have these rock-eating bugs, essentially, that are eating simple inorganic molecules, and they’re doing this under very Mars-like conditions, in this frozen world,” says Whyte, an astrobiologist at McGill University in Montreal, Canada.
The search for extraterrestrial life has often focused on the Red Planet. Scientists believe that more than 3 billion years ago, Mars was warmer and wetter than it is today, and had a more protective atmosphere. While the planet is almost completely inhospitable to life now, researchers envision past Martian microbes eking out a life—or even flourishing—at the frigid, mucky bottom of some pond. Scientists have been sending rovers to trundle along the surface to hunt for evidence of such long-extinct alien microorganisms, and a drone copter to scout the path ahead. But it’s expensive—and difficult—to send a sampling expedition to Mars. Canada is a heck of a lot closer, and it’s not a bad proxy.
The Lost Hammer Spring has a number of unique attributes that mimic parts of the Martian landscape, Whyte says. First, there’s the subzero temperature (about -5 Celsius), as well as the extreme saltiness of the water—25 percent salinity, about 10 times as salty as seawater. (The salt keeps the water liquid, preventing it from freezing over.) Mars has been found to have salt deposits here and there, some of which might have been in brines eons ago, which perhaps would have been the last habitable spots on the planet. The water at Lost Hammer is nearly devoid of oxygen, at less than 1 part per million, which is uncommon on Earth but not on other worlds. Any creature holding out there counts as an “extremophile,” because it survives in bleak conditions on the fringe of where life can exist at all.
On each of their trips to the remote Canadian region, Whyte and his colleagues scooped up samples of the briny mud, each just a few grams. Back at their lab, they used machines to isolate microbial cells and sequence their genomes and RNA to figure out what the microbes use for energy and how they tolerate the conditions in the spring. That could aid astronomers’ efforts to figure out where and how microbes might be sustained on Mars or other worlds.
“From a Mars analogue perspective, this study is really cool,” says Janice Bishop, an astrobiologist at the SETI Institute in Mountain View, California. The Lost Hammer Spring might resemble the region on the western side of Mars’ Olympus Mons, the tallest peak in the solar system. There, from time to time in the past, brines might have percolated up through the permafrost, generating flowing cold springs, Bishop argues. Streaks seen on Mars could be signs of those past water flows.
Mars analogues have become a popular area of research, with scientists investigating life on the dry, mountainous terrain of Hawaii and Chile, as well as the basalt-dominated volcanoes of Iceland, for example. The subzero, salty brines of Lost Hammer Spring, as well as in a couple places in Antarctica, should be included in such lists of otherworldly places on Earth. But exactly how microorganisms persist there will require more detailed research.
“This is the first study I’m aware of where they’ve characterized the microbes,” Bishop says.
The team’s genetic analysis showed how the creatures could be consuming methane and other inorganic compounds, an encouraging conclusion considering the recent discovery of methane on Mars. (But geological processes could produce methane too, so its presence isn’t a smoking gun that proves life existed there.)
Research like Whyte’s could inform choices about where to send rovers or landers in the future, including the European Space Agency’s ExoMars mission later this decade. However, a genetic analysis like this could only be performed on Earth, not handled remotely by rovers, which means these missions would need to extract samples to be sent back to Earth. (Perseverance, NASA’s newest Mars rover, is in the process of coring rock samples that will be left in a cache for a future retrieval mission.)
“I really think there’s a lot of value in exploring polar regions and cataloging our understanding, because we have a wealth of information in the microbial genomes,” says Jill Mikucki, a microbial ecologist at the University of Tennessee at Knoxville, whose recent research has involved studying cold brines in Antarctica. “This teaches us and trains us for how we might do some of these analyses if we get samples returned from Mars, for example with the Mars 2020 mission” with the Perseverance rover.
The team’s research is also promising for the search for life beyond the Red Planet, including in the briny, underground seas of ocean worlds. “The bugs we found at Lost Hammer are on the top of the list of the types of microorganisms that we hypothesize could live on Mars or on the icy moons of Enceladus or Europa,” Whyte says.
