Astrobiology may be the study of life off-world, but plenty of its discoveries take place here, on Earth. Take the latest revelation published in Science Advances, for example: two sizeable, hypersaline lakes have been found beneath a 500-meter (1,640-foot) floor of ice in the Canadian Arctic.
That doesn’t just make them the first subglacial lakes in the area – adding to the hundreds recently found worldwide – but the first hypersaline subglacial lakes known to science on Planet Earth. It also, as the team suggest, points us toward the stars.
Although samples of the water down there are yet to be taken, the international team – led by the University of Alberta – suspect that they “may represent significant and largely isolated microbial habitats,” untouched by the outside world.
“If life exists in these lakes, it could have evolved in isolation since the area was last overridden by glacier ice, which was at least 120,000 years ago,” they explain in their study. In this sense, then, they may be comparable to ice-covered brine lakes on planetary bodies across the Solar System, including within Mars’ polar ice caps and inside Jupiter’s Europa.
In the past few years, scientists have found various analogs on Earth, from the microbial to the environmental, that suggest that there are several ways that life could thrive beneath the Jovian moon’s subglacial seas.
Just recently, a bacterium discovered within a mine shaft was found to be living off nothing more than water and the byproducts of irradiated sulfur-bearing minerals – thought by some to be a comparable environment to the seafloor of Europa. This latest study, then, suggests yet another environment on this celestial sphere – and others – that may be conducive to resilient microbial life.
These two new subglacial lakes were discovered using ground-penetrating radar, similar to how vast canyons and subglacial lakes were originally spotted beneath the Antarctic Ice Sheet. The NASA-derived data was actually being used to study the geology of the Devon Ice Cap, but inadvertently revealed the presence of these lakes, which aren’t connected to any external water sources.
Water at that depth should be frozen, but turns out that it wasn't, even at temperatures of -18°C (-0.4°F). There aren’t many ways to keep water liquid in those conditions, but one possibility – salinity – stood out.
The more salt you have, the lower the water’s freezing point, and the team estimate that the unexpectedly liquid water down there is four to five times saltier than average seawater.
The next step, apart from conducting more detailed surveys of these lakes – 5 and 8 square kilometers (1.9 and 3.1 square miles) respectively – is to obtain samples of the water down there. If microbial life is uncovered, then what form would it take?
“Microbes that grow in high salt concentrations are called halophiles, and they actually require the salt to survive,” Dr Ben Libberton, a microbiologist at the MAX IV Laboratory in Lund, Sweden, who was not involved in the paper, told IFLScience.
Although this could mean you’ve got bacteria down there, you're far more likely to find members of the Archaea domain, a recently discovered, difficult-to-isolate form of microscopic life. “We understand much less about archaea than we do about bacteria,” Libberton added.
With that in mind, these lakes aren’t just a geological revelation, but potentially a microbiological boon too, both for this world and others in the starry ocean above.