Perseverance reconstructs Lake Martian history and identifies rocks with potential to harbor fossils

The first scientific analysis of the images produced by the Perseverance rover points out that it actually landed in a great place to look for previous signs of Martian life. Jezero Crater has had a rich water history, with a lake that was stable until some 3.7 billion years ago.

The work, published in this week’s issue of the journal Science, is the first to bring results from NASA’s most recent mission to the red planet.

Even from a distance, the rover was able to collect detailed images of the region where, from orbit, scientists already saw a formation similar to a dry river delta leading into the crater. Portraits of parts of the western edge, including a structure informally named Kodiak, were taken with the Mastcam-Z camera and the SuperCam 2.2 km away. His analysis was led by Nicolas Mangold, from the University of Nantes, in France, and Sanjeev Gupta, from Imperial College, London, and reveals several layers of sediment deposition in various sections of the slope.

A As an example of what happens on Earth, this layered stratification allows us to infer the geological history of how those rocks were formed. And, in the case in question, they tell a very interesting narrative that is consistent with the prevailing view of the past of Mars.

The lower layers, therefore older, form a pattern of horizontal deposition and narrate the crater’s history to about 3.7 billion years ago. They indicate a constant flow of water into the lake, consistent with the idea that Mars, until that time, was a warmer, wetter place and stably harbored liquid bodies on its surface.

The date is relevant as, here on Earth, the first uncontroversial traces of life found in Greenland date back to the same time (3.7 billion years ago), although there are some possible even older microfossils (4.1 billion of years) in Australian rocks and even more remote ones (4.3 billion) in Canada. Mars and Earth were formed, along with the other planets of the Solar System, around 4.5 billion years ago.

The upper layer, more recent, witnesses another phase of the planet. There are whole rocks amidst the sediments, indicating occasional high-energy fluxes. Mars became episodically “wet” at the beginning of the drying process that led to the current stage, where water (almost) never flows on the surface. “This sedimentary succession indicates a transition, from sustained hydrological activity in a persistent lake environment, to highly energetic, short-lived river flows,” the researchers wrote.

Representation of the dimension of the lake during the formation of the first layers of the Kodiak formation (blue), compared to the estimated dimensions of the lake at its widest moment, made with orbital images (black outline). The star indicates the site Octavia E. Butler, landing site for Perseverance. (Credit: Mangold et. al/Science)


An important part of the work was to indicate potential paths for the future of the Perseverance mission, whose main objective is to search for potential molecular evidence (so-called “biosignatures”) of past life on Mars .

From the images, at the bottom of the slopes, the authors identify promising layers of what appear to be finely grained mud stones and clay, rock types that could theoretically preserve traces of ancient biology on the red planet — that if there was in fact anything alive there in the distant past.

Over the next few months, Perseverance should move towards the delta, a crossing that should offer some challenges, given the unevenness of the terrain. The rover arrived on Mars on 762 February 904 and in the first months it traveled relatively. close to its landing region, although it has already advanced 2.6 km. It is currently at rest, awaiting the end of the temporary alignment between Mars and the Sun that prevents communication with Earth. With the return to operations at the end of this month, it should begin to move more vigorously towards this formation closer to the western edge of the delta.

In addition to carrying out chemical composition analyzes of rocks in soil , Perseverance has the mission to collect and store samples for future shipment back to Earth. Many scientists believe that unambiguous evidence of Martian life can only be obtained when these rocky cores are studied in detail in terrestrial laboratories. But, in what is an important advance for the mission, the scientists already have important targets to study and sample.

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