Researchers have been thinking about it for a long time, it is now official: Perseverance has indeed landed in an ancient Martian lake.
Perseverance that has roamed Mars since last February has never ceased to shower us with superb images. And after three months of collection, the machine has accumulated a real little treasure. According to NASA teams, these pictures are irrefutable proof that the rover is in an old lake!
Jezero Crater – where the rover landed – had been suspected for a long time to be an ancient body of water. This is even one of the reasons why NASA had chosen to deposit Perseverance there. The American space agency was thus hopeful of being able to confirm this hypothesis, and it is now done.
From space, the Mars Reconnaissance Orbiter and other spacecraft gave us tantalizing hints about Jezero Crater’s watery past. Now that the @NASAPersevere rover is providing close-ups from the ground, scientists have encountered some geological surprises: https://t.co/9tXmiFNsDS pic.twitter.com/ern4PqRkV6
– NASA Mars (@NASAMars) October 7, 2021
The works published in the journal Science are based on the study of an area that has already intrigued researchers for some time. Indeed, the latter has a particular appearance, fan-shaped. This is reminiscent of the deltas that can be found on Earth. Perseverance therefore left to conduct its investigation in the field, and produced several photos of geological beds invisible from orbit.
A lake, a river, and huge floods
By analyzing the photos, the researchers noticed that the structure of the rock layers corresponded perfectly to their expectations. On Earth, this kind of structure is formed by a process of sedimentation. A phenomenon that researchers have therefore found here on Mars.
The photos were even of such good quality that NASA was able to analyze the different layers in detail. Based on their orientation and thickness, researchers from the American agency deduced that this material could only have been deposited by fluids in motion. This indicates that the crater was at some point in its history a placid lake, fed by a small river.
But their conclusions do not end there. They also spotted large rocks in the upper layers. A not trivial find; this means that they were deposited rather recently (all things considered) in the geological history of Mars. But given their size and weight, they certainly weren’t moved by a simple river. According to the researchers, this presence testifies to an episode huge floods, which occurred in record time.
A geological and biological safe
For scientists, the presence of water in the crater in the past is great news in many ways. In the first place, they will now be able to go back to the source from these floods, and thus learn more about the climatology, hydrology and geology of Mars. Even better: this water could have possibly served as a substrate for a form of life. It will therefore be all the more interesting to go upstream in search of traces of past life.
This is all the more true as on Earth, these structures, already very instructive in themselves, often contain fossils trapped between two layers of sediment. These outcrops are therefore real safes. They contain some of the geological, and hopefully, biological history of the Red Planet. It only remains to explore its content; a long-term adventure, but infinitely exciting. “It will take time to find the rocks where we hope to find signs of life”, Concludes Benjamin Weiss, researcher in planetary sciences at MIT. “It’s a marathon, but with a lot of potential.”The text of the study is available here.