New evidence for ancient Martian lake: possible subsurface biosphere?

Layers of sedimentary rocks on the bottom of McLaughlin Crater. Carbonate and clay deposits indicate this crater once contained a groundwater-fed lake.Credit: NASA / JPL-Caltech / University of Arizona
Layers of sedimentary rocks on the bottom of McLaughlin Crater. Carbonate and clay deposits indicate this crater once contained a groundwater-fed lake. Credit: NASA / JPL-Caltech / University of Arizona

There is new evidence from the Mars Reconnaissance Orbiter spacecraft for an ancient Martian lake that may have been an ideal habitable environment, it was announced yesterday.

The results come from an analysis of data of McLaughlin Crater, a large, deep crater at the lower end of a long regional slope in the Arabia Terra region. The crater is approximately 57 92 kilometres (57 miles) in diameter and 2.2 kilometres (1.4 miles) deep. A study of the crater’s structure and the presence of carbonate and clay deposits on the bottom of the crater suggest that it was once a lake fed by upwelling from subsurface groundwater. Similar groundwater-fed lakes are common on Earth.

According to Joseph Michalski, lead author of the paper, “Taken together, the observations in McLaughlin Crater provide the best evidence for carbonate forming within a lake environment instead of being washed into a crater from outside.”

The lake would likely have been non-acidic, or pH neutral, making it a suitable watery environment for possible life. Carbonates and clays are typically formed in such environments.

As MRO Project Scientist Rich Zurek summarizes, “This new report and others are continuing to reveal a more complex Mars than previously appreciated, with at least some areas more likely to reveal signs of ancient life than others.”

The new findings suggest that a deep subsurface biosphere was possible early in Mars’ history and that evidence of it may still be preserved today. If such a biosphere started on Mars, could it still be there now? While surface conditions are very inhospitable, there may still be pockets of groundwater or aquifers deeper underground where life could exist. Even if only traces of moisture were present, any putative microbes would still be protected from the harsh ultraviolet light on the surface.

The findings were published yesterday in the online edition of Nature Geoscience.

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Paul Scott Anderson is a freelance space writer with a life-long passion for space exploration and astronomy. He started his blog The Meridiani Journal in 2005, which is a chronicle of planetary exploration. He also publishes The Exoplanet Report e-paper. In 2011, he started writing about space on a freelance basis, and now also currently write for AmericaSpace and He has also written for Universe Today and SpaceFlight Insider, has been published in The Mars Quarterly and has done supplementary writing for the well-known iOS app Exoplanet for iPhone and iPad.

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