HomeScienceOuter SpaceThe ancient lakes of Mars could help discover life on the red...

The ancient lakes of Mars could help discover life on the red planet

Since robotics explorers began to visit the Red Planet in the 1960s and 1970s, scientists have marveled at the surface features of Mars. These include stream channels, valleys, lake beds, and deltas that appear to have formed in the presence of water.

Since then, dozens of missions have been sent to Mars to explore its atmosphere, surface and climate to learn about its warmer, wetter past. In particular, scientists want to know how long water flowed on the surface of Mars and whether it was persistent or periodic in nature.

The ultimate goal here is to determine whether rivers, streams, and standing bodies of water existed long enough for life to arise. So far, missions like Curiosity and Perseverance have amassed amounts of evidence showing how hundreds of large lake beds once dotted the Martian landscape.

But according to a new study by an international team of researchers, our current estimates of MarsSurface water might be a dramatic understatement. Based on a meta-analysis of years of satellite data, the team states that ancient lakes once common feature on Mars.

The research was led by Joseph Michalksic, an associate professor in the Department of Earth Sciences and the deputy director of the Laboratory of Space Research (LSR) at the University of Hong Kong (HKU). The new paper was published in the magazine Nature.

An example of a large impact crater-hosted lake on Mars (left)) and a small permafrost-hosted lake (right). Credit: ESA/JPL/NASA/ASU/MSSS

“Not all lakes are created equal”

As Michalski explained in a recent HKU press releasecurrent research has focused on larger bodies of water on Mars, possibly neglecting the many smaller lakes that may have existed there:

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“We know of about 500 ancient lakes that were deposited on Mars, but almost all of the lakes we know are larger than 100 km2. But on Earth, 70% of lakes are smaller than this size, which occurs in cold environments where glaciers have retreated. These small lakes are difficult to identify with satellite remote sensing on Mars, but there were probably many small lakes. It is likely that at least 70% of the lakes on Mars have yet to be discovered.”

Lakebeds are currently one of the main targets for robotic explorers on Mars, as ancient Lakes would possess all the ingredients for microbial light – including water, nutrients and energy sources such as light (for photosynthesis).

Today, the lake beds of these ancient bodies of water contain sedimentary deposits rich in iron/magnesium clay minerals and carbonates, as well as sulfates, silica, and chlorides. These deposits may contain surviving evidence that would attest to the ancient atmospheric and climatic conditions on Mars.

But as they point out in the paper, most of the known lakes on Mars date from the Noachian period (c. 4.1 to 3.7 billion years ago) and lasted only 1,000 to 1 million years. In geological terms, this is a relatively short span of time and represents a small fraction of the 400-million-year-old Noachian timeline.

This could mean that ancient Mars was also cold and dry, and that running water was occasional and short-lived. Because of Mars’ lower gravity and fine-grained soil, the team also theorized that the lakes on Mars would have been turbid, making it difficult for light to get very deep and posing a challenge to photosynthesis.

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As a result, Michalski and his colleagues argue that large, ancient, ecologically diverse lakes would be a much more promising target for future exploration.

“Not all lakes are created equal,” Michalski said. In other words, some lakes on Mars would be more interesting for microbial life than others because some lakes were large, deep, long-lived and had a wide variety of environments, such as hydrothermal systems that could be conducive to the formation of the simple to live.”

However, there is also evidence that lakes existed on Mars during more recent geological periods, but that they left fewer traces. These include paleolakes in the Hesperian period (3-3.7 billion years ago) and shallow swampy lakes during the Amazon Basin (less than 3 billion years ago).

Earth analogues

These features would be similar to those on Earth, where similar cold conditions exist, and would likely resemble shallow lakes in drier regions (Hesperian) and thermoclasts (swampy hallows) that occur during permafrost thaws (Amazon).

Canada’s Pingualuit Crater Lake is a contemporary example of a cold-impact crater-hosted lake on Earth, analogous to ancient crater lakes on Mars.Stocktrek Images / Stocktrek Images / Getty Images

David Baker is an ecologist at the HKU School of Biological Sciences and co-author of the paper who is well versed in microbial systems in Earth’s lakes. As he summed up, Earth analogs could help expand the search for life on Mars by allowing scientists to look into more diverse environments:

“Earth is home to many environments that can serve as analogs 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 in the house. Most of those instruments are aimed at detecting the remains and remnants of microbial life.”

This research supports the recently released ESA mineral map of Mars, which showed how aqueous minerals (which form in the presence of water) are ubiquitous on the surface.

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It can also help inform future robotics missions, including the ESAs Rosalind Franklin rover, currently scheduled for 2028. China’s first lander and rover mission to Mars, Tianwen-1 and Zhuronglanded on May 14, 2022 and is currently exploring the plains of Utopia Planitia.

This area was once the site of an ocean that covered most of the Northern Hemisphere, and likely contains mineralogical and chemical evidence of how and when Mars transitioned from a warmer, wetter planet to what we see today.

The Perseverance Rover is currently collecting and caching samples that will be retrieved by an ESA-NASA sample return mission in the coming years. This will be the first time samples from Mars will be returned for comprehensive analysis that can only take place in Earth-based labs.

China is planning a similar monster return mission that could be sent to a Hesperian or Amazonian lake bottom and is likely to take place by the end of the decade. These and other missions will also pave the way for manned missions, which NASA and China plan to deploy by the early 2030s.

These missions will land in regions with accessible water, which could serve as a site for potential research. If there was life on Mars billions of years ago (or still today), the evidence won’t remain elusive for much longer!

This article was originally published on Universe today by means of Matt Willems. Read the original article here.



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