Images of Mars from a NASA rover confirm the Jezero crater was once a lake fed by a small river about 3.7 billion years ago – and sediments found within could hold traces of life, say experts.
The first scientific analysis of the pictures indicates where the Perseverance rover shows how much water flowed into the crater.
It also reveals evidence that Jezero suffered flash floods.
Now scientists have confirmed the crater was once a lake, and they believe the sediments could contain traces of ancient aqueous life.
Scientists believe this delta is what remains of the confluence between an ancient river and a lake at Jezero. Pic: NASA/JPL-Caltech/ASU/MSSS
Perseverance will look for locations to collect and preserve samples, which will eventually be returned to Earth, where scientists can probe them for signs of Martian life.
“It will take some time to get to the rocks that we really hope to sample for signs of life. So, it’s a marathon, with a lot of potential,” said Tanja Bosak, associate professor of geobiology at MIT.
The findings are based on images of rocks from the crater’s western side.
Satellite pictures had shown the outcrop resembled Earth’s river deltas, where sediment layers are left in the shape of a fan as a river feeds into slower-moving or stagnant water.
The images taken by Perseverance from inside the crater confirm the Jezero outcrop was a river delta.
Ingenuity, the first powered aircraft to fly at another planet, arrived at Mars clinging to Perseverance’s belly.
The lake was calm for much of its life, according to the study, until a dramatic change in climate caused episodes of flooding.
Scientists say the flooding swept large boulders tens of miles, from highlands well outside the crater, and left them on the lake bed, where they remain today.
“If you look at these images, you’re basically staring at this epic desert landscape. It’s the most forlorn place you could ever visit,” said Professor Benjamin Weiss from the Massachusetts Institute of Technology (MIT).
“There’s not a drop of water anywhere, and yet, here we have evidence of a very different past.
“Something very profound happened in the planet’s history.”
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NASA footage of Mars rover’s landing
The NASA rover landed in the Jezero crater on 18 February – along with the Ingenuity Mars helicopter – and has been collecting samples and sending back images.
It’s due to spend at least two years exploring the area.
Professor Weiss added: “The most surprising thing that’s come out of these images is the potential opportunity to catch the time when this crater transitioned from an Earth-like habitable environment, to this desolate landscape wasteland we see now.
“These boulder beds may be records of this transition, and we haven’t seen this in other places on Mars.”
The study’s findings are published in the journal Science.