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A Most Unusual Lake – NASA Science

by Chief Editor
written by Chief Editor

Lake Untersee: An Antarctic Window into Earth’s Past and the Search for Life Beyond

Earth is home to over 100 million lakes, but few are as uniquely positioned to unlock secrets about our planet’s history – and the potential for life elsewhere – as Lake Untersee in Antarctica. Sealed beneath layers of ice, this unusual lake boasts exceptionally high oxygen levels, a strongly alkaline pH, and remarkably preserved microbial structures that offer a glimpse into Earth’s earliest ecosystems.

A Unique Chemical Composition

Lake Untersee’s water chemistry sets it apart. Unlike most lakes, it contains exceptionally high levels of dissolved oxygen and low levels of dissolved carbon dioxide. This unusual combination, coupled with its alkaline pH, creates a distinct environment that supports a unique ecosystem. The lake receives most of its water from seasonal meltwater draining from the Anuchin Glacier, but remains frozen year-round, with temperatures averaging around -10 degrees Celsius (14 degrees Fahrenheit).

Stromatolites: Living Fossils in the Ice

Perhaps the most fascinating aspect of Lake Untersee is the presence of large, conical stromatolites. These layered microbial reef structures are formed by photosynthetic microbes, primarily cyanobacteria, trapping sediment and creating calcium carbonate mineral crusts. Discovered in 2011, these formations are thought to be modern examples of the organisms that created some of Earth’s oldest fossils, found in places like southwestern Greenland and western Australia.

Unlike similar structures in Lake Joyce, which reach only a few centimeters tall, the stromatolites in Lake Untersee can tower up to half a meter. Scientists believe this is due to the lake’s sheltered environment beneath permanent ice, exceptionally clear waters, limited light, and a lack of grazing organisms. The largest creatures inhabiting the lake are microscopic “water bears,” known for their ability to survive extreme conditions.

A Glimpse into Early Earth

The stromatolites in Lake Untersee offer a rare opportunity to study microbial life as it existed over 3 billion years ago, when microbes were the only form of life on Earth. These structures provide valuable insights into the conditions that supported early life and how these organisms interacted with their environment.

Analog for Extraterrestrial Environments

Lake Untersee isn’t just important for understanding Earth’s past; it also serves as a potential analog for environments on other planets and moons. Astrobiologists point to the lake as a possible model for icy moons like Europa and Enceladus, which are believed to harbor subsurface oceans. The lake’s conditions may also resemble those that existed on early Mars, which had ice caps and glaciers.

Dynamic Ecosystems Beneath the Ice

Despite its seemingly stable conditions, Lake Untersee is not immune to change. In 2019, researchers observed a 2-meter rise in the lake’s water level caused by a glacial lake outburst flood from nearby Lake Ober-See. This flood released 17.5 million cubic meters of meltwater, altering the lake’s pH and replenishing it with carbon dioxide-rich waters, potentially boosting microbial productivity.

Future Research and Exploration

Ongoing research at Lake Untersee continues to reveal fresh insights into its unique ecosystem and its potential as an analog for extraterrestrial environments. Scientists are using data from NASA’s ICESat-2 satellite to monitor changes in the lake’s water level and ice cover, and are conducting further studies of the stromatolites and microbial communities.

Frequently Asked Questions

  • What makes Lake Untersee unique? Its unusual water chemistry – high dissolved oxygen, low carbon dioxide, and alkaline pH – combined with the presence of large stromatolites.
  • Where is Lake Untersee located? In the interior of the Gruber Mountains in central Queen Maud Land, East Antarctica.
  • Why are stromatolites important? They are layered microbial reef structures that provide insights into early life on Earth and may resemble structures that could exist on other planets.
  • What is the significance of the glacial lake outburst flood? It demonstrates that even seemingly stable Antarctic lakes can experience abrupt changes, and that these changes can have a significant impact on the ecosystem.

Pro Tip: The extreme conditions in Lake Untersee make it a challenging environment for research, requiring specialized equipment and techniques.

Want to learn more about the fascinating world of Antarctic lakes and the search for life beyond Earth? Explore more articles on our site and subscribe to our newsletter for the latest updates!

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Scoria Cones on Earth and Mars

by Chief Editor
written by Chief Editor

Mars’ Volcanic Past: Unearthing Explosive Secrets

For decades, planetary geologists have known that Mars is covered in volcanic features. The discovery of massive shield volcanoes and lava plains by missions like Mariner 9 in the 1970s revealed a planet dramatically shaped by volcanic activity. Now, new research is focusing on a less common, but equally important, aspect of Martian volcanism: explosive eruptions.

The Puzzle of Explosive Volcanism on Mars

Olympus Mons, the solar system’s largest volcano, and Alba Mons, its widest, were primarily built by relatively calm lava flows. However, a smaller portion of Martian volcanism was produced by explosive events, creating volcanic cones, pyroclastic flows, and ashfalls. Interestingly, despite Mars’ thinner atmosphere and lower gravity – conditions that theoretically should *encourage* explosive eruptions – these features are surprisingly rare.

Petr Brož, a planetary geologist with the Czech Academy of Sciences, notes that the scarcity of explosive volcanic features has long puzzled researchers. Recent discoveries, like the volcanic cones found in Mars’ Ulysses Colles region, are providing crucial clues.

Analogous Landscapes: Earth’s San Francisco Volcanic Field

To better understand these Martian features, scientists are turning to Earth for comparison. The San Francisco Volcanic Field in northern Arizona provides a striking analog. NASA’s Landsat 8 captured images of scoria cones in Arizona, which closely resemble those observed on Mars by the Mars Reconnaissance Orbiter’s Context Camera (CTX). Both locations too exhibit grabens – linear blocks of crust that have shifted downward.

These scoria cones are formed by “mildly explosive” Strombolian events, characterized by intermittent lava fountains. Although not as violent as eruptions like the one at Hunga Tonga-Hunga Ha’apai, they represent a significant departure from the predominantly effusive volcanism previously thought to dominate Mars.

What Martian Cones Notify Us

The presence of scoria cones suggests that explosive volcanism played a more significant role in shaping the Martian surface than previously understood. Researchers have identified tens to a few hundred potential cones on Mars, compared to the tens of thousands found on Earth. This disparity raises questions: was explosive volcanism simply less common on Mars, or have these features been obscured by later lava flows or erosion?

Patrick Whelley, a NASA volcanologist, emphasizes the value of studying analogous features on Earth. “Understanding similar features on Earth helps us know what to look for on Mars and interpret processes that You can’t observe directly.” SP Crater in Arizona, for example, is used for NASA astronaut geology training due to its similarities to Martian volcanic landscapes.

Beyond Scoria Cones: Super Eruptions and Future Research

While scoria cones offer insights into smaller explosive events, Mars also shows evidence of massive “super eruptions.” These events leave behind different geological signatures, such as large depressions called paterae and broad ash deposits sculpted into yardangs.

However, interpreting Martian geology requires caution. As Brož points out, features that *look* volcanic may not always be. Mud volcanoes, for instance, can mimic the appearance of scoria cones. His laboratory research suggests that mud flows on Mars can even resemble lava flows under certain conditions.

Determining the sequence of events – whether lava flows preceded cone formation or vice versa – remains a key challenge. Further research, including potential future missions to Mars, will be crucial to unraveling the planet’s complex volcanic history.

Frequently Asked Questions

  • What are scoria cones? Scoria cones are steep-sided hills formed from the accumulation of volcanic fragments (scoria) ejected during explosive eruptions.
  • Why is studying Martian volcanism important? Understanding Martian volcanism provides insights into the planet’s internal structure, thermal evolution, and potential for past habitability.
  • How do scientists study Martian volcanoes remotely? Scientists use data from orbiting spacecraft, such as the Mars Reconnaissance Orbiter and Landsat 8, to analyze the morphology and composition of volcanic features.
  • Are there active volcanoes on Mars today? Currently, there is no evidence of active volcanism on Mars, but the planet is not considered geologically dead.

Pro Tip: Planetary comparison is a powerful tool for understanding distant worlds. By studying analogous features on Earth, scientists can gain valuable insights into the geological processes that have shaped other planets.

Explore more about Mars’ geology and ongoing research at NASA’s Mars Exploration Program.

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