The Jezero Crater on Mars, now an arid and windy depression, was a calm lake 3.7 billion years ago, points to the first scientific analysis of images from NASA’s Perseverance rover.
Analysis of the images, published yesterday in the scientific journal Science, shows that there are signs of flash flooding in the crater from a small river that fed the lake and carried large rocks downstream from the bottom of the lake.
The floods, according to the analyzed evidence, were strong enough to carry large stones for tens of kilometers, which later deposited at the bottom of the lake, where they remain to this day.
The conclusion is based on images of rocks exposed to the interior of the crater from the western side. Satellite images have already shown this outcrop, which when viewed from above resembles river deltas on Earth, where sediment layers form a fan-like shape.
New images of Perseverance, taken from inside the crater, confirm that this outcrop was actually a river delta. Based on the sedimentary layers of the outcrop, scientists speculate that the river flowed into a calm lake for most of its existence, until an abrupt change in climate caused episodic floods at the end or near the end of the lake’s existence.
“If you look at these images, you will mainly see this epic desert landscape. This is the most desolate place you could ever visit, ”said Benjamin Weiss, research team member and professor of planetary sciences in the Department of Science. Earth, Atmospheric and Planetary at MIT (Massachusetts Institute of Technology, Private University in Cambridge, USA).
“There is not a drop of water anywhere, but still here we have evidence of a completely different past. Something very important has happened in the history of the planet, ”added the scientist quoted in a statement revealing image analysis.
Scientists hope to find more clues about the evolution of Mars’ climate as Perseverance explores the crater. Now that they have confirmed that the crater was once a lacustrine environment, they believe the sediments may contain traces of aquatic life. The robotic vehicle will collect sediment, which can be sent to Earth and thus studied.
“We now have the ability to search for fossils,” said researcher Tanya Bosak, assistant professor of geobiology at MIT, who is part of the group that analyzed the images.
Perseverance landed at Jezero Crater on February 18, just over a mile (1.6 km) from the western delta. The vehicle was stationary for the first three months, while NASA engineers performed remote checks on many of the instruments on board. During this period, two cameras took pictures of the surroundings.
By sending images to Earth, scientists observed individual layers of sediment and concluded that these sediments must have been deposited by water flowing into the lake, and not by wind or other geological processes.
Other images have led scientists to conclude that the fan-shaped formation actually belonged to an ancient river delta.
“Without moving anywhere, the rover was able to solve one of the big unknown problems – that this crater was once a lake,” said Benjamin Weiss.
The scientists explain that since the huge rocks that will be washed away by major floods are in the upper layers of the delta, it is because they are newly deposited material as they settle in the upper layers of older and smaller sediments. This indicates that for most of its existence, the ancient lake was fed by a peacefully flowing river.
