from robotics explorers began visiting the Red Planet during the 1960s and 1970s, scientists have been puzzled by the features of the Martian surface. These included flow 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 more about its warmer, wetter past. In particular, scientists want to know how long the water flowed on the surface of Mars and whether it was persistent or periodic in nature.

The ultimate purpose here is to determine whether rivers, streams, and bodies of standing water existed long enough for life to emerge. Until now, missions like Curiosity Y Perseverance have amassed volumes 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 surface water on Mars may be a dramatic underestimate. Based on a meta-analysis of years-old satellite data, the team argues that ancient lakes may have once been a very common feature on Mars.

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

“Not all lakes are the same”

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

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

Lake beds are currently one of the top targets for robotic explorers on Mars because ancient lakes would have all the ingredients for microbial light, including water, nutrients, and energy sources such as light (for photosynthesis) .

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

But as they indicate in the article, most of the known Martian lakes date from the Noachian Period (approximately 4.1 to 3.7 billion years ago) and lasted only between 1,000 and 1 million years. In geological terms, this is a relatively short period of time and represents a small fraction of the Noachian timeline of 400 million years.

This could mean that ancient Mars was also cold and dry, and that the flowing water was episodic and short-lived. Due to the lower gravity and fine-grained soil of Mars, the team also theorized that lakes on Mars would have been murky, making it difficult for light to reach very deep and presenting challenges for photosynthesis.

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

“Not all lakes are the same,” Michalski said. “In other words, some Martian lakes would be more interesting to microbial life than others because some of the lakes were large, deep, long-lived, and had a wide range of environments, such as hydrothermal systems, that might have been conducive to their formation. of the simple life.”

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

earth analogues

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

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

“Earth hosts many environments that can serve as analogs to other planets. From the harsh terrain of Svalbard to the depths of Mono Lake, we can figure out how to design tools to detect life elsewhere right here at home. Most of these tools are aimed at detecting remains and residues of microbial life”,

This research reinforces ESA’s recently published mineral map of Mars, which showed how aqueous minerals (those that form in the presence of water) are ubiquitous on the surface.

It could also help inform future robotic missions, including ESA’s. rosalind franklin rover, which is currently scheduled to launch in 2028. China’s first rover and landing mission to Mars, tianwen-1 Y zhuronglanded on May 14, 2022 and is currently exploring the plains of Utopia Planitia.

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

the Perseverance The 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 that samples have been brought back from Mars for extensive analysis that can only be carried out in terrestrial laboratories.

China is planning a similar sample-return mission that could be sent to a Hesperian or Amazon lake bed and will likely happen by the end of the decade. These and other missions will also pave the way for manned missions, which NASA and China plan to mount in the early 2030s.

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

This article was originally published on universe today by matt williams Read the original article here.