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Lake Mercer, a subglacial lake located beneath the Antarctic ice, has remained intact for millennia – until now.
Scientists accidentally discovered the lake in 2007, while they were examining satellite images of the Antarctic ice cap. Then on December 26, 2018, they finally succeeded.
To explore the subglacial lake at a depth of 15 meters, researchers at a project called SALSA (Scientific Access to Antarctic Subglacial Lakes) had to drill a tiny hole nearly a kilometer away from the ice cream. To do this, they used a drill with a pencil-sized nozzle that sprayed heated water. Once the hole was done, they then used a coring tool to bring the samples back to the surface.
The team members planned to find microbial life forms in these samples – and they did – but they were surprised by what was hiding in the mud. The samples also contained carcasses of tiny crustaceans (creatures smaller than a poppy seed) and the body of a tardigrade, a type of eight-legged invertebrate known for its ability to withstand the conditions the most extreme.
A surprise in the mud
The SALSA team eventually extracted a core 5.5 feet long (the longest in a subglacial lake) as well as "six cores of sediment" perfect. "They also filled six bottles of 10 liters with from the lake water and captured the very first images of the lake.The fruits of their work were repatriated to the McMurdo Ice Station, for analysis, according to the project blog SALSA.
When the researchers discovered the bodies of tiny crustaceans and a tardigrade in the samples, Priscu was so surprised that he thought the discovery was a mistake. He was convinced that the carrots had been contaminated, Nature reported. He asked the team to thoroughly clean their equipment and take other samples.
When the new samples came back, they were: no more shellfish shellfish. Nothing like it had never been found under a layer of ice before.
Mercer Lake is the second subglacial lake that scientists have accessed. They also drilled 2,600 feet deep to reach nearby Whillans Lake in 2013, but samples collected there show no evidence of higher life forms (only microbes).
Microbial life probably exists in this mud under the ice, as an ocean covered the region about a million years ago, said SALSA chief scientist John Priscu at Axios. But this does not explain the origin of the carcasses.
Instead, the discovery suggests that these crustaceans and tardigrades once lived on the mainland; they have somehow been transported to the lake from the nearby mountains (where such creatures have already been found). Depending on the nature, moving water could have transported them or a glacier would have dragged them as they progressed.
How to reach a lake under the ice
The subglacial Antarctic is a highway of hydraulic works.
Streams and rivers connect hundreds of masses of water under the ice, and this network has changed during the history of Antarctica. Understanding how continental ice responds to changes in Earth's climate helps scientists better understand its history.
"Antarctica is the least affected place by man on Earth. It is therefore an extraordinary laboratory for understanding life and biodiversity, as well as glacial history. of our planet, "said Business Insider Ross Virginia, director of the Institute of Arctic Studies at Dartmouth College.
In addition, studying Antarctic waterways is a crucial means of monitoring the potential consequences of global warming.
"The evolution of ice sheets and ice trays is one of the leading controllers of sea level rise," Virginia said.
But searching the subglacial systems of Antarctica is incredibly difficult.
Virginia has been working for nearly 30 years in the dry valleys of Antarctica and has collaborated with Priscu on other Antarctic research projects. Drilling in these environments, he said, requires the same kind of care as that taken by NASA when exploring new worlds in space, "such as quarantining astronauts returning from the moon or the maintenance of sterile equipment ".
This is because contamination can easily ruin expensive and important research, or even lead scientists to think they have discovered a type of life that does not really exist.
"We are still concerned about the contamination," said Victoria. "You do not want to introduce the surface organisms to enclose the underground ecosystems."
That's why good equipment is crucial.
The SALSA team used a corer – which is essentially a tube that screws into the ice – from the Woods Hole Oceanographic Institute. Although the hole they had drilled was no more than 60 centimeters wide, the researchers were able to slide this core along the chute length of nearly a kilometer. After touching the sediments, the corer – and the lake mud that he seized – were brought to the surface.
Paving the way for drilling in other extreme environments
As drilling operations were so difficult and complex, the SALSA project could offer lessons to continue research into other extreme environments, perhaps even on other planets.
Drilling in Antarctica is about as close as scientists can understand what it would take to drill in the liquid ocean on the Moon of Jupiter, Europa, said Mark Skidmore, professor of science and technology. Earth at Montana State University, Axios.
Experts believe that Europa's oceans are one of the most likely places to find extraterrestrial life in our solar system.
"We are learning more about the types of technologies and processes and how to proceed, as well as what you will discover in these types of environments," Skidmore told Axios.
But drilling under the Antarctic also benefits us on Earth
Virginia's main concern is that large floating ice caps that extend continental margins of Antarctica melt from below, thanks to the warming of the water. (Last year was the hottest year ever recorded for the Earth's oceans.)
When ice caps melt, they lose their structural integrity. If they disintegrate, it could mean that an influx of continental ice would spill into the ocean – an event called "impulse" that would contribute to a rapid rise in sea level.
"The leaves act like a dam," Virginia said.
In a certain way, Antarctica reacts to climate change and exerts control over the climate of the Earth. He said: "The history of the Antarctic climate is linked to that of the world".
