Mars Might Have Been Covered in Lakes in the Ancient Past

Scientists have been puzzled over the surface features of Mars since robotic explorers first visited the Red Planet in the 1960s. Flow channels, valleys, lakebeds, and deltas appear to have formed in the presence of water Dozens of missions have been sent to Mars to investigate its atmosphere, surface, and climate. Scientists want to know if water flowed on the surface of Mars for a long time or if it was intermittent.

The purpose of this is to find out if rivers, streams, and standing bodies of water existed long enough for life to begin. The evidence gathered by the missions shows how many large lakebeds once dotted the landscape. Our current estimates of the amount of water on Mars may be overstated according to a new study. The team believes that ancient lakes may have once been a common feature on the planet.

The leader of the research was a professor at the University of Hong Kong. He was joined by researchers from the Canadian Institute for Advanced Research, the Center for Planetary Systems Habitability, the Natural History Museum, and Brown and Georgetown University. The paper that describes their findings was published in the journal Nature.

Current research has focused on larger bodies of water on Mars, potentially neglecting the smaller lakes that may have existed there.

“We know of approximately 500 ancient lakes deposited on Mars, but nearly all the lakes we know about are larger than 100 km². But on Earth, 70% of the lakes are smaller than this size, occurring in cold environments where glaciers have retreated. These small-sized lakes are difficult to identify on Mars by satellite remote sensing, but many small lakes probably did exist. It is likely that at least 70% of Martian lakes have yet to be discovered.”

Lakebeds are currently one of the prime targets for robotic explorers on Mars because ancient lakes have all the ingredients for microbial light. There are iron/magnesium clay minerals and carbonates in the lakebeds of these ancient bodies of water. Evidence from the ancient atmospheric and climatic conditions on Mars could be found in these deposits.

The paper indicates that most of the lakes on Mars are from the Noachian Period. It lasted for less than one million years. This is a small portion of the 400 million-year Noachian timelines. It's possible that ancient Mars was cold and dry. The team believes that lakes on Mars would have been murky, making it difficult for light to reach deep and presenting challenges for photosynthesis.

The lakes that are large, ancient, and diverse would be a more promising target for future exploration. Some lakes are created better than others. Some of the lakes on Mars were large, deep, long-lived, and had a wide range of environments that could have been favorable to the formation of simple life.

There is evidence that there were lakes on Mars in the past. During the Hesperian Period, there were paleo lakes and shallow marshy lakes in the Amazon. These features would be similar to those found on Earth where similarly cold conditions exist and would likely resemble shallow lakes found in dry areas.

The co-author of the paper is an ecologist at the HKU School of Biological Sciences who knows a lot about lakes. Earth analogs could be used to expand the search for life on Mars by allowing scientists to look in more diverse environments.

“Earth is host to many environments that can serve as analogs to other planets. From the harsh terrain of Svalbard to the depths of Mono Lake – we can determine how to design tools for detecting life elsewhere right here at home. Most of those tools are aimed at detecting the remains and residues of microbial life,”

The research supports the recent release of the mineral map of Mars, which shows how water-bearing minerals are abundant on the surface. The Rosalind Franklin rover, which is scheduled to launch by 2028, is one of the robotic missions that could be helped by it. The first lander and rover mission to Mars from China landed in May of 2022.

This region was once the site of an ocean that covered most of the northern hemisphere and contains evidence of how and when Mars transitioned from a warm, wet planet to a cold, dry one. The Perseverance rover is currently collecting and caching samples that will be retrieved by a sample return mission in the near future. This will be the first time that samples from Mars will be analyzed in Earth-based laboratories.

By the end of the decade, China will likely send a sample-return mission to a lakebed in the Hesperian or Amazon basin. The way for crewed missions will be paved by these and other missions. The missions will land in regions that have access to water, which could double as a site for research. If there was life on Mars billions of years ago, the evidence won't be hard to come by for a long time.

Nature and HKU are read further.