Mars today is a dry and inhospitable desert. But billions of years ago, it might have looked a lot like Earth, with liquid water flowing across its surface. Now, new analysis of data from the Perseverance rover confirms that Jezero Crater, where the rover is currently exploring, was once a large lake and was even prone to flash floods. The presence of water supports the possibility that life may once have flourished on Mars.
The analysis is based on images of rocks on the west side of Jezero Crater, which appears to be a river delta. Here layers of sediment have been deposited in a fan shape that closely resemble river deltas on Earth where a river flows into a lake. An international team of researchers has found that the sedimentary layers confirm the presence of an ancient lake that was calm throughout its life, but was then dramatically inundated.
“If you look at these pictures, you’re basically looking at this epic desert landscape. This is the most desolate place you can visit, ”said Benjamin Weiss, professor of planetary science in the Department of Earth, Atmospheric and Planetary Sciences at MIT and member of the analysis team. . “There isn’t a drop of water nowhere, and yet here we have proof of a very different past. Something very profound has happened in the history of the planet.
The researchers were able to say that there had been significant flooding due to the presence of large rocks up to 1 meter in diameter that were embedded in the younger layers of the delta. These large boulders must have come from outside the crater, having been transported a distance of 40 miles or more by enormous flooding. The fact that they are based on many older layers shows that the flooding must have occurred late in the lake’s history.
“You need drastic flood conditions to haul such big and heavy rocks,” Weiss said. “It’s a special thing that may indicate a fundamental change in local hydrology or perhaps the regional climate on Mars.”
Researchers have long believed that Jezero was once a lake, hence the choice of this location for Perseverance to explore, but this could not be fully confirmed until the rover visited the site and collected data. Now, they can be sure that there was once abundant water and was present long enough that life potentially emerged.
“We now have the opportunity to search for fossils,” said Tanja Bosak, team member, professor of geobiology at MIT. “It will take some time to reach the rocks that we really hope to sample for signs of life. So it’s a marathon, with a lot of potential.
The results are published in the journal Science.
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