Scientists believe that these bands of rock may have been formed by a very fast and deep river: the first such evidence has been found on Mars. NASA’s Mars rover Perseverance captured this view using its Mastcam-Z camera between February 28 and March 9, 2023, at a location called “Scrinkle Haven.”New images obtained by NASA’s Perseverance rover may show signs of a once mighty river on Mars, which may have flowed deeper and faster than scientists had evidenced in the past. The river was part of a network of waterways that emptied into Jezero Crater, the area the rover is exploring since it landed more than two years ago.
Understanding these aqueous environments will aid scientists in their efforts to find signs of ancient microbial life that may have been preserved in Martian rocks.
Perseverance is exploring the top of a fan-shaped clump of sedimentary rock that is 250 m (820 ft) tall and shows curved layers suggesting a water current. One question scientists want to answer is whether that water flowed in relatively shallow streams — more like Gale Crater based on evidence from NASA’s Curiosity rover — or in a more powerful river system.
Two new mosaics pieced together from hundreds of images captured by Perseverance’s Mastcam-Z instrument suggest the latter, revealing important clues: coarse sediment grains and pebbles.
“These materials indicate a high-energy river that would transport large amounts of debris. The more powerful the flow of water, the more powerful the flow of water,” said Libby Ives, postdoctoral researcher at NASA’s Jet Propulsion Laboratory (JPL) in Southern California. Ives, an expert in the study of Earth’s rivers, has spent the past six months analyzing images of the Red Planet’s surface. It’s such a pleasure to look back and see processes that are so well known.”
Years ago, scientists observed a series of curved bands in layers of rock inside Jezero Crater that they called “curved units”. They’ve been able to see these layers from space, but now they can finally see them up close, thanks to Perseverance.
A location within the rotating unit, dubbed “Scribble Haven,” is captured in one of Mastcam-Z’s new mosaics. Scientists are convinced that the curved layers here were created by a powerful flow of water, but the detailed Mastcam-Z shots have left them debating what kind of flow it would have been: a river like the Mississippi, sweeping through the landscape. Meandering, or like a braided flow, the Nebraska Plateau, which forms small islands of sediment called shoals.
When viewed from the ground, the eroded layers appear to be arranged in rows that extend across the landscape. They may be the remains of a riverbed that changed over time, or may be the remains of sandbanks that formed in the river. In the past the layers were probably too many. Scientists suspect that after these clumps of sediment became rocks, they were eroded by the wind over billions of years and sculpted into their present shape.
“The wind acted like a scalpel that cut through the top of these reservoirs,” said Caltech researcher Michael Lamb, a river expert and contributor to the persistence science team. “On Earth we see deposits like this, but they are never as exposed as they are here on Mars. Earth is covered with vegetation that hides these layers.
The second mosaic taken by Perseverance shows a different location that is part of the Winding Unit and about a quarter mile (450 m) away from Skrinkle Haven. The “pinestand” is an isolated hill with sedimentary layers that lean towards the sky, some up to 20 meters (66 ft) high. Scientists believe that these upper layers may also have been formed by a mighty river, although they are also exploring other explanations.
“These layers are unusually high for rivers on Earth,” Ives said. “But at the same time, the most common way to form these types of landforms would be a river.”
The team continues to study the Mastcam-Z images for additional clues. They’re also looking below the surface, using a ground-penetrating radar instrument called the Radar Imager for the Subsurface Mars Experiment (RIMFAX). What they learn from both instruments will contribute to an ever-expanding body of knowledge about Mars’ ancient aquatic past.
“The exciting thing here is that we have entered a new phase in Jezero’s history. And this is the first time we’ve seen an environment like this on Mars,” said JPL Perseverance Deputy Project Scientist Katie Stack Morgan. “We’re thinking about rivers on a different scale than before.”
more about the mission
A major goal for the Perseverance Mars mission is astrobiology, which includes searching for signs of ancient microbial life. The rover will characterize the planet’s past geology and climate, pave the way for human exploration of the Red Planet, and will be the first mission to collect and store Martian rocks and regoliths (loose rock and dust).
Subsequent NASA missions, in collaboration with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis.
The Mars 2020 Perseverance mission is part of NASA’s Moon to Mars exploration focus, which includes the Artemis mission to the Moon that will help prepare humanity for exploration of the Red Planet.
JPL, which is managed by Caltech for NASA in Pasadena, California, built and manages the operations of the Perseverance rover.
For more information about Perseverance, visit the website: mars.nasa.gov/mars2020/