Dale Andersen enters a world cut off from the rest of Antarctica. As he descends on the rope, he sees small conical structures called stromatolites at the bottom of the lake. These 12 to 24 inch cones are formed over eons, in a submillimeter layer, by a genus of cyanobacteria called Phormidium.
Until Andersen and colleagues discovered stromatolites, they had never been found in the modern setting and were only a memory of when all Earth’s microbes were inhabited.
“This is like a postcard from 3 billion years ago,” Andersen says. “If you wanted to visualize what the ecosystem was like in those days, these Antarctic lakes provide a wonderful analogue of the ancient microbial world.”
A window into the past and other planets
Andersen is a senior research scientist at the Carl Sagan Center for the SETI Institute, a research organization dedicated to finding and studying life and intelligence beyond Earth.
Although Andersen has been visiting Lake Untersee for more than a decade, he still marvels at the unique aspect of its conical landscape. In fact, he points out, “More people have walked on the surface of the Moon than I have personally seen at the bottom of this pond.”
“Understanding those paleoenvironments or early biospheres on our planet is the first important aspect of understanding how the search for life proceeds elsewhere,” says Andersen.
“For example, when we investigate these Antarctic analogs, we think they will give us the first glimpse of Mars. The microbial ecosystems there, perhaps not exactly the same as those seen in the Antarctic lakes, but end and similar. After”
“Working with the stromatolitic communities of the lake helps inform the search for life in the paleolacustrine sediments of Mars. The anaerobic regions of the southern lake of Lake Untersee help us focus on what it will be like to search for life in the oceans. Enceladus and Europa, the outermost moons of Jupiter and Saturn.”
YSI measures water quality
Located in the mountains of Queen Mathilda in East Antarctica, Lake Untersee is covered in ice year round. In order to reach Lake Untersee, a multidisciplinary research team flees to Antarctica from Cape Town, South Africa, and lands at Russia’s Novolazarevskaya ice research station. From there, the team must cross the ice for a day on a snowmobile.
Then they set up camp and began drilling the ice hole. To make the hole, the team circulates hot water through a cylindrical coil that constantly melts through the ice to create access to the diving lake. This is a process that can take more than 24 hours. Smaller holes, 25 centimeters in diameter, are used for lower instruments and obtain water samples.
Andersen is very concerned about collecting measurements of water quality throughout the water column. It uses a YSI EXO2 multi-parameter probe with smart sensors for turbidity, total algae, pH, oxidation-reduction potential (ORP), fluorescent dissolved organic matter (fDOM), dissolved oxygen (DO), and conductivity.
By slowly lowering the probe – a meter or even half a meter at a time – and keeping an eye on the program, the team can detect subtle changes in temperatures, oxygen levels, and chemical composition.
The impact of global warming
Under the ice Lake Untersee is usually a very calm environment with very slow water circulation. According to Andersen, it took about a month for the particles to travel the 6.5 kilometer length of the lake. But from time to time unexpected incidents arise.
Analyzing satellite altimetry data, Andersen and colleagues found a two-meter sudden rise in the water level of Lake Untersee in early 2019. The mother ice apparently erupted into Lake Obersee about four miles away, releasing 17.5 million cubic meters. water in Lake Untersee for three weeks.
Based on subsequent observations and measurements, Andersen says it is likely an event that lasted between 300 and 500 years. When he returned to Lake Untersee in November 2019, Andersen immediately directed a multi-parameter survey to measure the lake’s water quality.
“We saw a major change in water chemistry because of this flood event,” Andersen said. “These measurements are important and the kind that help us understand the impacts that global warming will have on the microbial ecosystem of the Untersee in the coming year.”
As Andersen describes exploring the world beneath the Antarctic ice sheet, NASA continues to transmit gigabytes of images of the Martian surface. Although Perseverance runs more than 280,000 kilometers from Lake Untersee, the two worlds meet in images from both places as if they were posible for scientists, eager to understand the origins of life on our planet and to look for signs of life elsewhere.
