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NASA’s Perseverance Mars rover team have confirmed that the Red Planet’s Jezero Crater was once the site of a delta-lake system.
In a study published Thursday in the journal Science, researchers also wrote that images of the rover – taken within three months after Perseverance landed in February – suggest the area has experienced significant late-stage flooding.
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The images were taken of long, steep slopes called escarpments, or “escarpments”, in the delta, which are believed to have formed from sediment at the mouth of an ancient river that fed into the lake.
Photos revealed that the fan-shaped delta had outcrop faces that the team said were invisible from orbit and record the hydrologic evolution of the crater.
The “Kodiak” rock outcrop had only been photographed from orbit, but the images revealed its stratigraphy along the east face, showing layers that a geologist would expect to find in the delta of a. river on Earth.
This image of “Kodiak” – a remnant of the fan-shaped sediment deposit inside the Jezero crater of Mars known as the delta – was taken by Perseverance’s Mastcam-Z instrument on February 22, 2021 .
(Credits: NASA / JPL-Caltech / ASU / MSSS)
“We interpret the presence of sloping strata in these outcrops as evidence of deltas that have advanced into a lake. In contrast, the upper fan strata are composed of conglomerates of boulders, implying deposition by episodic high floods. energy, ”the study authors wrote. “This sedimentary succession indicates a transition from sustained hydrological activity in a persistent lacustrine environment, to short-lived, highly energetic river flows.”
“Never before has such a well-preserved stratigraphy been visible on Mars,” said Nicolas Mangold, Perseverance scientist at the Laboratory of Planetology and Geodynamics in Nantes, France, and lead author of the article, in a press release. NASA. “This is the key observation that allows us to confirm once and for all the presence of a lake and a river delta in Jezero. road.”
The photos that led them to these conclusions were taken by Perseverance’s left and right Mastcam-Z cameras in addition to its remote micro-imager.
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NASA said the images also provided the team with insight into where they could best search for rock and sediment samples to collect and cache.
Further up the escarpments, Mastcam-Z and RMI found stones and boulders that the team said must have been washed away by rapid flash floods.
“These results also have an impact on the strategy for selecting rocks to sample,” Sanjeev Gupta, Perseverance scientist at Imperial College London and co-author of the article, said in a statement. “The thinnest material at the bottom of the delta probably contains our best bet for finding evidence of organics and biosignatures. And the rocks at the top will allow us to sample old pieces of crustal rock. Both are primary goals. for sampling and caching rocks before the sample returns from Mars. “
This annotated image shows the locations of NASA’s Perseverance rover (bottom right), as well as the “Kodiak” Butte (bottom left) and several steep banks known as escarpments or escarpments, along from the Jezero crater delta.
(Credits: NASA / JPL-Caltech / University of Arizona / USGS)
Finally, scientists described the water level in Lake Jezero as fluctuating several tens of meters before it disappeared – although it is not known whether the changes resulted from flooding or more gradual environmental changes.
The team determined that the changes occurred later in the history of the delta and that lake levels were at least 330 feet below the highest level.
“A better understanding of the Jezero Delta is essential for understanding the changing hydrology of the region,” Gupta noted, “and this could potentially provide valuable information on why the entire planet has dried up.”
NASA believes that Mars dried up around 3.5 billion years ago and that the lake existed around 3.7 billion years ago.
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The delta will be the site of the rover team’s second scientific campaign in 2022.
“We now have the ability to search for fossils,” team member Tanja Bosak, associate professor of geobiology at MIT, told MIT News. “It will take a while to get to the rocks that we are really hoping to sample for signs of life. So it’s a marathon, with a lot of potential.”
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