Lake Mercer, a subglacial lake well below the Antarctic Ice, remained intact for millennia, until now.
The scientists accidentally discovered the lake in 2007, when they were examining satellite images of the Antarctic ice sheet. Then, on December 26, 2018, they finally reached it.
To explore the subglacial lake 50 meters deep, researchers of a project called SALSA (Scientific Access of the Subglacial Antarctic Lakes) had to drill a small hole almost 1 kilometer in the ice. They did it using a drill with a pencil-sized nozzle that sprays hot water. Once the hole was made, they used a corer tool to extract samples from the surface.
The team anticipated finding microbial life forms in those samples, and they did, but they were surprised by what was lurking in the mud. The samples also contained corpses of small crustaceans (creatures smaller than a poppy seed) and the body of a tardigrade, an eight-legged invertebrate type known for its ability to withstand the harshest conditions.
A surprise in the mud.
The SALSA team ended up extracting a 5.5-foot long core (the longest of a subglacial lake) along with "six of six perfect" sediment cores. "They also filled six 10-liter bottles of lake water and captured the first images of the lake According to the blog of the SALSA project, the fruits of their work were transported to the McMurdo ice station for badysis.
When the researchers discovered the bodies of small crustaceans and a tardigrade in the samples, Priscu was so surprised that he thought the finding was wrong. He was convinced that the nuclei had been contaminated, Nature reported. So he had the team clean up their equipment again and take more samples.
When the new samples returned, there they were: more crustacean shells. Never before had such a thing been found under a layer of ice.
Lake Mercer is the second subglacial lake to which scientists have agreed. They also drilled 2,600 feet down to reach nearby Whillans Lake in 2013, but samples taken there showed no signs of higher life forms (only microbes).
Most likely there is microbial life in this mud under the ice because an ocean covered the area about a million years ago, said the chief SALSA scientist, John Priscu, to Axios. But that does not explain the origin of the corpses.
Instead, the discovery suggests that these crustaceans and tardigrades once lived on the continent; Somehow, they were transported to the lake from nearby mountains (where such creatures have been found before). The moving water could have transported them, or a glacier may have dragged them along as it went, according to Nature.
How to get to a lake under the ice.
Subglacial Antarctica is an interstate hydraulic works.
Streams and rivers connect hundreds of bodies of water under the ice, and this network has changed throughout the history of Antarctica. Understanding how the continent's ice responds to changes in Earth's climate helps scientists understand more about its history.
"Antarctica is the place on Earth least touched by humans, and as such, it is an amazing laboratory for understanding life and biodiversity, and the glacial history of our planet," said Ross Virginia, director of the Institute of Arctic Studies from Dartmouth College, to Business Insider.
In addition, studying the waterways of Antarctica is a crucial way to control the possible consequences of global warming.
"The evolution of ice sheets and ice shelves are the main drivers of sea level rise," said Virginia.
But researching the subglacial systems of Antarctica is incredibly difficult.
Virginia has been working intermittently in the dry valleys of Antarctica for almost 30 years, and has worked with Priscu on other Antarctic research projects. Drilling in these environments, he said, requires the same kind of care that NASA takes when exploring new worlds in space, "like quarantining astronauts returning from the Moon or maintaining sterile equipment."
This is because pollution can easily ruin expensive and important research, or even lead scientists to think that they have discovered a kind of life that does not really exist.
"We are always worried about pollution," said Victoria. "You do not want to introduce surface organisms to enclosed subsoil ecosystems."
That's why a good team is crucial.
The SALSA team used a corer, which is essentially a tube that is screwed into the ice, from the Woods Hole Oceanographic Institute. Although the hole they drilled was no more than 60 centimeters wide, the researchers were able to slide that column through the almost one kilometer long conduit. After it hit the bottom sediment, the corer and mud from the lake it grabbed were removed to the surface.
Paving the way for drilling in other extreme environments
Because the drilling operation was so difficult and complex, the SALSA project could offer lessons for conducting research in other extreme environments, perhaps even on other planets.
The drilling in Antarctica is as close as scientists can get to understanding what it would take to drill the liquid ocean on Jupiter's moon, Europe, Skios Mark Skidmore, a professor of Earth science at the State University of Montana.
Experts believe that Europe's oceans are one of the most likely places to find extraterrestrial life in our solar system.
"We are learning about the types of technologies and processes and how you would do it, and we learn what you will find in those types of environments," Skidmore told Axios.
But drilling under Antarctica also benefits us on Earth
Virginia's biggest concern is that the large floating ice sheets that stretch from the continental margins of Antarctica are melting from below due to warming water. (Last year was the warmest year recorded for Earth's oceans).
As the ice sheets melt from below, they lose structural integrity. If they disintegrate, that could mean that a wave of continental ice would flow into the ocean, an event called "pulse" that would contribute to a rapid rise in sea level.
"The sheets act like a dam," said Virginia.
In a way, Antarctica responds to climate change and exercises control over Earth's climate, he said: "The history of the Antarctic climate is connected to the globe."