Only the toughest organisms can thrive in one of the coldest springs on earth. Therefore, in the summers of 2017 and 2019, Lyle Whyte took a helicopter to Lost Hammer Spring in the uninhabited high-arctic region of Nunavut, Canada. Snow, ice, salt tuff, rocks and permafrost surround the modest spring, which is surrounded by almost barren, treeless mountains on the island of Axel Heiberg, a few hundred kilometers from the North Pole. He had traveled to this place outside of this world to study the microbes that live in its salty, icy, oxygen-poor waters, hoping to learn about what life could have been like if it ever appeared in similar places – on Mars.
In a new magazine 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 sediment can actually survive the harsh environment. Most soils are either directly or indirectly dependent on solar energy. But these microbes can survive on a chemical energy source: They eat and inhale inorganic compounds like methane and hydrogen sulfide, making the area smell like rotten eggs, even from a distance. (The research team’s pilot calls the site the “stinking springs.”) “You essentially have these stone-eating insects that eat simple inorganic molecules, and they do so 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 Mars more than 3 billion years ago was warmer and wetter than it is today, and had a more protective atmosphere. While the planet is almost completely inhospitable to life now, scientists imagine that former Mars microbes will have a life – or even bloom – on the cold, muddy bottom of a pond. Scientists have sent rovers to roll along the surface to hunt for evidence of such long-extinct alien microorganisms and a drone copter to scout the way ahead. But it is expensive – and difficult – to send a test expedition to Mars. Canada is much closer and it is not a bad proxy.
The Lost Hammer Spring has a number of unique features that mimic parts of the Martian landscape, Whyte says. First, the temperature is below zero (about -5 Celsius) as well as the extreme salinity of the water – 25 percent salinity, about 10 times as salty as seawater. (The salt keeps the water liquid and prevents it from freezing.) Mars has been shown to have salt deposits here and there, some of which could have been in brine forever, which might have been the last habitable spots on the planet. The water at Lost Hammer is almost devoid of oxygen, with less than 1 part per million, which is uncommon on Earth, but not on other worlds. Any creature that stays out there counts as an “extremophile” because it survives in gloomy conditions on the outskirts of where life can even exist.
On each of their trips to the remote Canadian region, Whyte and his colleagues picked up samples of the salted mud, each weighing only a few grams. Back in their lab, they used machines to isolate microbial cells and sequence their genomes and RNA to find out what the microbes use for energy and how they tolerate spring conditions. It could help astronomers’ efforts to find out where and how microbes can be maintained on Mars or other worlds.