Researchers have yet to find life on other worlds, but recent discoveries show that many of the bodies in our Solar System, including planets and moons, may harbor vast reserves of water ice. Frozen worlds, as distant as Pluto, could even possess liquid water, in the form of salty lakes and oceans under their surface.
Here on Earth, life thrives anywhere there is an adequate supply of water, even under the harshest conditions. In an effort to learn more about how primitive lifeforms could evolve on frozen environments in space, a team of researchers explored cryopegs, trapped layers of salty water and sediment in the frigid environment of the Arctic. The samples were collected between 2017 and 2018.
“The extreme conditions here are not just the below-zero temperatures, but also the very high salt concentrations. One hundred and forty parts per thousand — 14% — is a lot of salt. In canned goods that would stop microbes from doing anything. So there can be a preconceived notion that very high salt should not enable active life,” said Jody Deming, a professor of oceanography from the University of Washington who specializes in studying microbial life in the Arctic Ocean.
This is Carrying Pickling to the Extreme
Brine samples from a cryopeg in Alaska, isolated for as long as 50,000 years, were subjected to DNA sequencing, revealing thriving colonies of bacteria. These lifeforms were shown to be similar, but not identical, to those found in floating sea ice and salt water which flows around glaciers.
“Cryopegs make up the only habitat on Earth that is characterized by permanently subzero temperatures, high salinity, and isolation from the influence of external factors during geological time” EDU Arctic explains.
Cryopegs were first discovered in northern Alaska several decades ago. During the 1960’s, the site of this exploration in Utqiaġvik (once known as Barrow), was excavated in order to explore large wedges of freshwater ice that form in the permafrost of the region.
Researchers taking part on these excavations took turns climbing down a 12-foot ladder into the ice, where they spent four to eight hours collecting samples.
Geologists are still uncertain how cryopegs form, although they may develop from coastal lagoons that became covered in ice during the most recent ice age. Moisture may have evaporated from these waterways, which were then covered with permafrost, trapping the briny water beneath the frozen soil.
The dominant bacteria found in the cryopegs were Marinobacter, a form of Proteobacteria which make their lives in sea water.
“We’re just discovering that there’s a very robust microbial community, coevolving with viruses, in these ancient buried brines. We were quite startled at how dense the bacterial communities are,” Zachary Cooper, a doctoral student in oceanography at the University of Washington, stated.
There’s Water on That World!
“The surface of the Earth is the shore of the cosmic ocean. From it we have learned most of what we know. Recently, we have waded a little out to sea, enough to dampen our toes or, at most, wet our ankles. The water seems inviting.” — Carl Sagan
Several planets and satellites in our Solar system, as well as our Moon, are now known to be home to significant supplies of water. This suggests that finding life in our Solar System, however primitive, is more likely than once believed.
Upcoming crewed launches to the Moon are directed at the south pole of our satellite, where spacecraft have detected deposits of water ice. Frozen deposits of water ice are found beneath the surface of Mars, as well as on Europa and Ganymede, two of the large Moons of Jupiter. Orbiting Saturn is the massive moon Titan, where oceans of methane and ethane interact with water, creating an environment that is one of the most likely places to find life beyond the Earth. Even in the asteroid belt between Mars and Jupiter, the giant asteroid Ceres is home to a vast ocean of liquid water. Recent findings suggest that even distant, frozen Pluto may play host to a subsurface ocean of liquid water. The cryopegs that were the subject of this study could closely resemble deposits of water on other worlds in the Solar System.
“Cryopegs… can contain subzero brines that have been derived from atmospherically exposed and then frozen marine sediments that become isolated over long periods of time, a physical process similar to what may have occurred early in Mars history,” researchers explain in an abstract of a presentation delivered at the 2019 Astrobiology Science Conference.
We may soon find life beyond the Earth, but to recognize these bizarre lifeforms, we will need to know what to look for in these alien environments. Looking beneath the Arctic ice may be a wise place to gather the knowledge needed for what will be the greatest discovery in history.
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