The Perseverance rover captures new images of ancient river evidence

Editor’s note: Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news of amazing discoveries, scientific advances, and more.

Pasadena, California
CNN
–

A raging river may have cut through Mars billions of years ago.

The rover has captured new images that appear to reveal geological evidence of a fast-flowing river that feeds Jezero Crater, the site of an ancient Martian lake.

Perseverance has begun exploring the remnants of the environment inside the crater, which now resembles a dried-up lake bed, after landing on the Red Planet in February 2021.

The rover began studying fan-shaped deposits in the 820-foot (250-meter) area, which are likely remnants of an ancient river delta, about a year ago. First, he studied the persistence of the worn leading edge of the propeller. Now, the rover has climbed above the fan to explore sedimentary rocks that might be preserving evidence of water and past life, if they ever existed.

“This fan really represents the major history of the water in the crater,” Katie Stack Morgan, deputy project scientist for Perseverance at NASA’s Jet Propulsion Laboratory, told CNN. “With the rover, we’re actually moving through different environments that water was once associated with. So here in Jezero, we have evidence of ancient lakes, deltas, and rivers.”

The fan’s curved layers indicate that it was shaped by flowing water, and the latest images taken by the rover indicate a deeper river moving faster than scientists expected on Mars. It’s the first time scientists have seen environments like this on Mars.

Scientists have long been curious about the diverse types of waterways that existed on Mars more than 3 billion years ago, when the planet was much warmer and wetter. Previous observations by the Curiosity rover, which landed on Mars in 2012 and is exploring Gale Crater about 2,300 miles (3,700 kilometers) away, revealed shallow streams rather than strong rivers.

The most recent persistence results, collected in two mosaic images, show pebbles and coarse-grained sediment.

“These refer to a high-energy river that is trucking in and carrying a lot of debris. The stronger the flow of water, the more easily it can move larger pieces of material,” Libby Ives, a postdoctoral researcher at JPL, said in a statement.

Rivers likely carried larger rocks and debris from other regions on Mars to Jezero Crater, Morgan said.

One of the mosaics shows a deposit called the Skrinkle Sanctuary, where flowing waters carved out layers of rock that remained after billions of years. Scientists aren’t sure if the rows of rocks that seem to ripple across the landscape resemble the shifting banks of the Mississippi River or the island-like sandbars of Nebraska’s Platte River.

The rock strata were probably much taller in the past but have been eroded by wind over time.

“The wind acted like a scalpel that cut off the tops of these sediments,” Michael Lamb, a river specialist and collaborator on the Perseverance Science team at Caltech, said in a statement. “We see deposits like this on Earth, but they’ve never been exposed like they are here on Mars. The Earth is covered in vegetation that hides these layers.”

Also noted is the “Pinestand”, an isolated hill formation filled with layers of confined sedimentary rock that curves skyward up to 66 feet (20 m) high.

“These layers are abnormally long for rivers on Earth,” Ives said. “But at the same time, the most common way to create these types of terrain is by river.”

perseverance and search for life

Scientists use all the tools in the Perseverance suite to get to the bottom of the mysterious river, including the rover’s ground-penetrating radar for the Mars Subsurface Experiment, or RIMFAX, to search below the site. The Perseverance team is also analyzing other images taken by the rover.

The rock and dirt samples collected by the probe will eventually travel back to Earth via the aspiration Mars Sample Return Programa series of successive missions scheduled for the next decade that will venture to the Red Planet, capture samples from Perseverance’s cache and return them to scientists for analysis in laboratories around the world.

“One of the reasons we chose Jezero as a landing site is because the more diverse the rocks we have, the better chance we have of learning more about the processes that occurred on Mars and shaped Mars,” Morgan said. “We have different types of habitable environments recorded within these rocks.”

Samples of Martian rocks and soil may reveal whether life ever existed on Mars.

“To answer that question, we have to bring these rocks back to Earth, where we have really sophisticated instruments and laboratories that can investigate deeply into this question,” Morgan said. It is a difficult question to answer. We even struggle with early Earth rocks to answer this question. But the task of Perseverance is to identify those rocks that have the best chances of life in them, and we’ve been able to do that.”