Super salty, subzero Arctic water provides a sneak peek at the possible life on other planets


people in the ice cave

Zac Cooper and Shelly Carpenter start drilling under the Alaskan ice tunnel towards the criopola and its subzero salt water. Researchers are careful to sterilize their equipment to avoid introducing contamination from the ground. The most rigorous techniques will be needed to sample life on other planets. Go to Iwahana / University of Alaska, Fairbanks

In recent years, the idea of ​​life on other planets has become less far-fetched. NASA announced June 27 that it will send a vehicle to Saturn's icy moon Titan, a celestial body known to host superficial methane lakes and an ocean of ice water, increasing its chances of sustaining life.

On Earth, scientists are studying the most extreme environments to learn how life could exist in completely different contexts, like on other planets. A team from the University of Washington studied the microbes found in "cryopegs, "Trapped sediment layers with water so salty that it remains liquid at temperatures below zero, which could be similar to environments on Mars or other planetary bodies further from the sun.

To the recent AbSciCon meeting in Bellevue, Washington, the researchers presented DNA sequencing and related results to show that the brine samples of an isolated Alaska cryopean for tens of thousands of years contain thriving bacterial communities. Life forms are similar to those found in floating ice and salt water flowing from glaciers, but show some unique patterns.

"We really study old sea water trapped inside permafrost up to 50,000 years, to see how those bacterial communities evolved over time," he said. Zachary Cooper, doctoral student in oceanography in oceanography.

The cryopegs were first discovered by northern Alaska geologists decades ago. This field site in Utqiaġvik, formerly known as Barrow, was excavated over the years by the research and engineering laboratory of the cold regions of the US military to explore large freshwater ice wedges that they occur in permafrost there. Subsurface brine was eventually withdrawn from the site in the 2000s.

staircase diagram and cave

A scheme of the study site, which consists of a tunnel, dug by a massive ice formation in the permafrost and accessible through a narrow vertical opening. The researchers then drill under the tunnel floor to reach the criopola layer with its saline liquid (dotted area). Shelly Carpenter / University of Washington

"The extreme conditions here are not just sub-zero temperatures, but also very high salt concentrations," he said Jody Deming, Professor of Oceanography of the UW who studies the microbial life in the Arctic Ocean. "One hundred and forty parts per thousand – 14% – is very salty. In canned products that would prevent microbes from doing anything. So there may be a preconceived notion that very high salt should not allow active life."

It is not completely known how cryopoles are formed. Scientists believe that the layers could be former coastal lagoons blocked during the last ice age, when the rain turned into snow and the ocean receded. The moisture evaporated from the abandoned bottoms was then covered by the permafrost, then the remaining water remained trapped under a layer of icy earth.

white landscape and people

The research site about 1 mile outside of Utqiagvik, Alaska, appears on the surface like a box on an expanse of white tundra. This is one of the two positions of the criopola studio in the world. It is not known how many of these features exist, but the evidence suggests that they are widespread in the coastal regions of the flat Arctic. Cooper Zac / University of Washington

To access the underground liquids, the researchers climb about 12 feet on a ladder and then carefully move along a tunnel inside the ice. The opening is of one person and is not high enough to stand up, so the researchers must squat down and work together to practice shifts from 4 to 8 hours.

wooden tunnel and person coming down ladder

Zac Cooper, a graduate student in Oceanography, climbs up a frozen staircase in the tunnel in May 2018. The researchers are harnessed to a rope for safety. Swelly Carpenter / University of Washington

Deming describes it as "exciting" because of the possibility of discovery.

The samples collected in the spring of 2017 and 2018, geologically isolated for what the researchers believe are around 50,000 years old, contain genes from communities of healthy bacteria along with their viruses.

"We are just discovering that there is a very robust microbial community that coexists with viruses in these ancient buried salt pans," said Cooper. "We were rather surprised by the density of bacterial communities."

Zac Cooper takes notes in the ice tunnel, with the light of his lighthouse. The team employs shifts from 4 to 8 hours inside the tunnel. A person gets the luxury of sitting on a bucket.

Zac Cooper takes notes in the ice tunnel, with the light of his lighthouse. The team shifts from four to eight hours of shifts inside the tunnel. A person gets the luxury of sitting on a bucket. Shelly Carpenter / University of Washington

Extreme environments on Earth can be similar to the oceans and ice of other planets, according to the scientist.

"The dominant bacterium is Marinobacter," said Deming. "Only the name tells us that it came from the ocean – even though it was in the darkness, buried in the frozen permafrost for a very long time, originally came from the marine environment."

ice crystals on the roof of the cave

The roof of the tunnel is covered with frost, the pointed ice crystals that form when the humidity in the air solidifies in the environment minus 6 degrees C of the tunnel. The underlying layers are cooler. Researchers leave pre-sterilized tubes inserted in the floor for future access to the underlying liquid layer. Zac Cooper / University of Washington

Mars once housed an ocean of water, and our solar system contains at least half a dozen oceans on other planets and frozen moons. Titan, the moon of Saturn that NASA will explore, is rich in various forms of ice. Studying life on Earth in icy environments that may have similarities can prepare explorers for what kind of life to expect and how to detect it.

The research was funded by the Gordon and Betty Moore Foundation to learn how bacteria and viruses combine in different marine environments. The other collaborators of UW are Josephine Rapp, post-doctoral researcher in Oceanography, Max Showalter, doctoral student in Oceanography, e Shelly Carpenter, a research scientist in Oceanography.

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