At one point, this region of Mars was inundated by a “mega-flood”

Through multiple robotic missions that explored the atmosphere, surface and geology of Mars, scientists have concluded that Mars was once a much hotter and humid place. As well as having a thicker atmosphere, the planet was actually warm enough that running water could exist on the surface in the form of rivers, lakes, and even an ocean that covered much of the earth. northern hemisphere.

According to a new study based on data collected by NASA Curiosity mission, it appears that Gale Crater (where the rover has been exploring for eight years) suffered massive flooding around 4 billion years ago. These results indicate that the mid-latitudes of Mars were also covered in water at one point, and offer additional clues that the region once supported life.

These findings were the subject of a study recently published in the Nov. 5 issue of Scientific reports on nature. The responsible research team was led by Dr. Ezat Heydari (professor of physics at Jackson State University) and included several Earth scientists, astronomers and researchers from NASA’s Jet Propulsion Laboratory (JPL), the Cornell University and the University of Hawaii.

On Mars, evidence of the planet’s aquatic past is written all over the landscape in the form of well-preserved geological features. Ironically, it’s the nature of today’s Martian environment – freezing cold, parched, no flowing water, and a very thin atmosphere – that has preserved this evidence over billions of years.

As they indicate in their study, the team analyzed the data obtained by Curiosity on the gravel ridges of the Hummocky Plains unit and the ridgeline and valley band formations in the ridged unit. These wave-shaped sedimentary deposits are what are called “megaripples” (aka. Antidunes). As co-author Alberto G. Fairén, visiting astrobiologist at the College of Arts and Sciences, explained to the Cornell Chronicle:

“We identified mega-floods for the first time using detailed sedimentological data observed by the Curiosity rover. The deposits left by the mega-floods had not previously been identified with the orbiter’s data. “

These antidunes at the bottom of Gale Crater are approximately 9 meters (30 feet) high and are spaced approximately 137 (450 feet) apart. In addition, they are dated to around 4 billion years ago and are identical to the layered sedimentary features on Earth that were deposited by the melting ice at the start of the Quaternary Ice Age (around 2 million d ‘years).

Here, too, the research team attributes the formation of these features to the melting ice, likely caused by a large impact that released carbon dioxide and methane from the planet’s frozen reservoirs. The resulting release of water vapor and gases combined to produce a greenhouse effect that led to a temporary increase in temperatures and wetter conditions.

As this water vapor cooled, it condensed to form clouds that led to torrential rains that could have been planetary. In Gale Crater, this water accumulated and combined with the water flooding Mount Sharp, located in the center of the crater. The result of all of this was a series of flash floods that created the mega-marpples at the bottom of the crater, which remained there intact after the water disappeared.

This latest evidence is yet another indication that Gale Crater once had persistent lakes and streams, as evidenced by sedimentary deposits. The presence of these long-lived bodies of water remains one of the strongest indications that microbial life could have existed in Gale Crater and Mount Sharp billions of years ago. As Fairén summed it up:

“The beginning of Mars was an extremely geologically active planet. The planet had the necessary conditions to support the presence of liquid water on the surface – and on Earth, where there is water, there is life. So early on, Mars was a habitable planet. Was it inhabited? That’s a question the next Perseverance rover… will help answer. “

On February 18, 2021, the Curiosity rover will be joined by its sister mission, Perseverance. Once on the surface, this robotic explorer will join the search for life on Mars (past and present) and will be the first mission to obtain samples for a possible return to Earth. Analyzing these will allow scientists to finally get a close-up glimpse of Martian soil and rocks, which may contain telltale signs of past life.

This mission, and others expected to arrive in the years to come, will help pave the way for possible crewed missions to Mars, which will settle on the Red Planet and attempt to unravel the lingering mysteries of its history and of its geological evolution.

Further reading: Cornell Chronicle, Scientific reports on nature