The number of ancient Martian lakes may have been greatly underestimated by scientists

Figure 1: Example of a large lake hosted from a crater on Mars (A) and a small lake hosted from permafrost on Mars. Both images show altitude data from the MOLA (Mars Orbital Laser Altimeter) instruments and HRSC High Resolution Stereo Camera) mounted on images from THEMIS (a) and CTX (b). Credit: ESA/JPL/NASA/ASU/MSSS

Lakes are bodies of water fed by rain and thaw, rivers and groundwater, through which the earth teems with life. The lakes also contain important geological records of past climates. Although Mars is a frozen desert today, scientists have shown that Mars contains evidence of ancient lakes that existed billions of years ago, which could contain evidence of ancient life and climate conditions on the Red Planet. Through a meta-analysis of years of satellite data showing evidence of lakes on Mars, Dr. Joseph Michalsky, a geologist in the Department of Earth Sciences, University of Hong Kong (HKU) suggested that scientists may have significantly underestimated the number of ancient Martian lakes that existed. From before.

Michalski and the international team recently published their findings in natural astronomy, which describes a global analysis of ancient Martian lakes. “We know of approximately 500 ancient lakes deposited on Mars, but nearly all of the lakes we know are larger than 100 km.2Michalsky explains. But on Earth, 70% of lakes are smaller than this size, and they occur in cold environments where glaciers are retreating. These small lakes on Mars are difficult to identify by satellite remote sensing, but there are likely many small lakes. It is possible that at least 70% of Martian lakes have yet to be discovered. “Scientists are monitoring these tiny lakes on Earth to understand climate change. The Missing Ones small lakes On Mars it may also contain important information about past climates.

The latest research paper also notes that most of the known Martian lakes date from 3,500 to 4,000 million years ago, but each of the lakes may have persisted for a geologically short period (10,000 to 100,000 years) during this time period. This means that ancient Mars may have been mostly cold and dry as well, but it warmed intermittently for short periods of time. Michalsky adds: “Because of the low gravity on Mars and the diffuse and fine-grained soil, the lakes on Mars were very murky and probably did not allow light to penetrate deeply, which could challenge photolithic life, if present.”

The number of ancient Martian lakes may have been greatly underestimated by scientists

Figure 2: Bingaloite crater lake in Canada is a recent example of a cold crater lake on Earth similar to ancient crater lakes on Mars. Credit: Google Earth

Lakes contain water, nutrients, and energy sources for potential microbial life, including light for photosynthesis. Therefore, lakes are the main targets of astrobiological exploration by Mars Rovers such as NASA’s Perseverance rover now on the surface of Mars. But Michalski warns, “Not all lakes are created equal. In other words, some Martian lakes would be more exciting for microbial life than others because some lakes were large, deep, long-lived and had a wide range of environments such as hydrothermal systems that would have helped form simple life.” “. From this point of view, it might make sense to target large, ancient, and ecologically diverse lakes for future exploration.

“Earth hosts many environments that could serve as analogues for other planets. From the rugged terrain of Svalbard to the depths of Mono Lake, we can determine how to design tools to detect life elsewhere here at home. Most of these tools are aimed at detecting remnants and remnants of microbial lifeDr David Baker, an ecologist at the University of Hong Kong’s School of Biological Sciences who is well informed about the Earth’s microbial systems in lakes, said.

China successfully landed its first lander, Zhurong, on the surface of Mars in May this year. Zhurong is currently roaming the plains of Utopia Planitia, exploring mineral and chemical clues to recent climate change. China is also planning a sample return mission likely to occur towards the end of this decade, which could target one of the lake’s interesting sediments.

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more information:
Joseph R. Michalsky et al., Geological Diversity and Microbiological Potential of Lakes on Mars, natural astronomy (2022). DOI: 10.1038 / s41550-022-01743-7

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University of Hong Kong

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