(Nicolas Mangold et al. / Science, 2021)
The Perseverance team presented the first results of sediment analysis in Jezero Crater, where the rover is currently operating.
They came to the conclusion that about 3-4 billion years ago there was a large closed lake in the crater, into which a river flowed, forming an extensive delta from sediment layers.
Mars today is cold and dry, but observations from rovers and orbiters show that its climate was milder in the past, and liquid water existed on the planet's surface.
To better understand exactly when it was, and whether Mars was inhabited at that time, NASA sent a new rover "Perseverance" to the red planet.
The mission has been operating since February this year in the 45-kilometer crater Jezero, where, according to scientists, about 3, 6-3.8 billion years ago there was a river delta that flowed into the lake.
Now, a team of planetary scientists led by Nicolas Mangold of the Laboratory of Planetology and Geodynamics at the University of Nantes has published the first results of studies of stratigraphy and sediment characteristics in the Jezero crater, based on images taken by rover cameras.
The study included four ledges of the river delta and the isolated Kodiak hill.
Previously, it was assumed that there was a system of open lakes in the Jezero crater, but now the researchers have come to the conclusion that Lake Jezero was closed
The lake not only didn’t have rivers flowing out of it on a permanent basis, but the water level in it was lower than previously thought.
A river flowed into the lake, which gradually formed sediments in the delta region.
In addition, the history of the lake has had repeated episodes of flooding of varying intensity, which could have been caused by heavy rainfall or events of rapid melting of snow or ice.
During floods, streams flowing at a speed of up to 9 meters per second along the riverbed could move very large and heavy boulders from the edges of the crater to the bottom of the lake.
Thus, the crater bottom is of interest from the point of view of searching for organic matter or biosignatures.
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