New images taken by NASA’s Perseverance rover may show signs of a raging river once on Mars that was deeper and faster than scientists had seen in the past. The river was part of a network of waterways that flowed into Crater Lake, an area the rover had explored since landing more than two years ago. Understanding these aquatic environments could aid scientists in their efforts to find signs of ancient microbial life that may have been preserved in Martian rocks.

Perseverance explores the top of a fan-shaped pile of sedimentary rock that is 820 feet (250 meters) high and has twisted layers resembling flowing water. One question scientists want to answer is whether this water flows in relatively shallow currents — closer to what NASA’s Curiosity rover has found evidence in Gale Crater — or a more powerful river system.

Two new mosaics, assembled from hundreds of images taken by Perseverance’s Mastcam-Z instrument, suggest the latter, providing important clues: coarse sediment grains and cobblestones.

“They show a high-energy river moving through a truck and carrying a lot of debris. The stronger the water flow, the more massive pieces of material are transported,” said Libby Ives, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory in Southern California, who runs the Perseverance rover. it would be that easy.” Ives, who has experience studying Earth’s rivers, has spent the last six months analyzing images of the surface of the Red Planet. “It was nice to look at rocks from another planet and see these kinds of familiar processes,” Ives said.

following the curves

Years ago, scientists noticed a series of curved layered rock bands in Jezero Crater that they called “curvilinear units.” They could see these layers from space, but they finally got the chance to see them up close, thanks to Perseverance.

One of Mastcam-Z’s new mosaics features a location called “Skrinkle Shelter” inside the curvilinear block. Scientists are sure that the meandering layers here were created by powerful flowing water, but the detailed Mastcam-Z images have them wondering which species it is: a river like the Mississippi that snakes its way across the land, or a meandering river like the Platte in Nebraska? small islets of sediment called sand bars.

NASA’s Perseverance rover captured this mosaic of a hill nicknamed “Pine Park.” Scientists believe that the overlapping high sedimentary layers may have been formed by a deep, fast-flowing river. Credits: NASA/JPL-Caltech/ASU/MSSS

Seen from the ground, the curved layers appear to be arranged in rows that diverge across the landscape. These may be remnants of river banks that have changed over time, or remnants of sandbars formed in the river. These layers were probably much higher in the past. Scientists suspect that after these sediment piles turned into rock, they were sandblasted by wind jets over the ages and carved to their current size.

“The wind acted like a scalpel, cutting off the tops of these deposits,” said Michael Lamb of the Cal Institute of Technology, a river expert and member of the Perseverance research team. “We see such deposits on Earth, but they are never as exposed here as on Mars. Earth is covered with vegetation that hides these layers.”

A second mosaic by Perseverance shows a separate area that is part of a curvilinear unit and is about 450 meters from Scrinkle Harbour. The “Pinestand” is an isolated hill containing upwardly curved sedimentary layers, some as high as 20 meters (66 feet). Scientists believe that these higher layers may also have been formed by a mighty river, although they are looking for other explanations.

“These layers are abnormally high for rivers on Earth,” Ives said. “But also, the most common way to create these landforms would be a river.”

The team continues to examine Mastcam-Z footage for more clues. They also look below the surface using Perseverance’s ground-penetrating radar instrument called RIMFAX (short for Radar Imager for Mars’ Underground Experiment). What they learn from both instruments will add to the ever-expanding body of knowledge about Mars’ ancient, watery past.

“What’s interesting is that we’ve entered a new phase in the history of Jezero. “This is the first time we’re seeing a similar environment on Mars,” said Katie Stack Morgan, Perseverance Project Associate Scientist at JPL. “We’re thinking of rivers at a different scale than before.”