NASA’s ‘Kodiak’ Moment of Perseverance on Mars – Jezero Crater Lake Is More Complicated and Intriguing Than You Think

Photos of NasaThe last six-wheeler on the Red Planet suggests that the region’s history has seen extensive flooding.

New article from NASA’s Perseverance science team March The rover explains how the hydrologic cycle of the now dry lake of Jezero Crater is more complicated and intriguing than originally thought. The results are based on the rover’s detailed imagery of long, steep slopes called escarpments or escarpments in the delta, which formed from sediment accumulating at the mouth of an ancient river that long ago fed the crater lake.

Images reveal that billions of years ago, when Mars had an atmosphere thick enough to support the flow of water on its surface, the Jezero fan-shaped river delta experienced flooding. late which transported rocks and debris from the highlands well outside the crater. .

Taken by the rover’s left and right Mastcam-Z cameras as well as its remote micro-imager, or RMI (part of the SuperCam instrument), they also provide insight into where the rover might best look for rock and sediment samples, including those that may contain organic compounds and other evidence that life once existed there.

The rover’s team have long considered visiting the delta because of its potential to harbor signs of ancient microbial life. One of the primary goals of the mission is to collect samples that could be brought to Earth by the multi-mission Mars Sample Return effort, allowing scientists to analyze the material with powerful lab equipment too large to be brought to Mars. .

The article on the Perseverance escarpment images – the first research to be published with data acquired after the rover landed on February 18 – was published online today in the journal Science.

“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.”

Perseverance ‘Kodiak’ Moment

At the time the images were taken, the escarpments were to the northwest of the rover and about 2.2 kilometers away. Southwest of the rover, and at about the same distance, is another major rock outcrop that the team calls “Kodiak.” In its ancient past, Kodiak was on the southern edge of the delta, which would have been an intact geological structure at the time.

Before Perseverance arrived, Kodiak had only been photographed from orbit. From the surface, Mastcam-Z and RMI images of the rover first revealed stratigraphy – the order and position of rock layers, which provides information about the relative chronology of geological deposits – along the east face. from Kodiak. The tilted and horizontal stratification there is what a geologist would expect to see in a river delta on Earth.

“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. “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. Better understanding the hydrology months before we arrived in the delta will pay big dividends on the road. “

While Kodiak’s results are significant, it was the story told by the images of the Northeast escarpments that came as the biggest surprise to the rover’s science team.

Move rocks

Imaging of these escarpments showed similar layering to Kodiak on their lower halves. But higher up on each of their steep walls and at the top, Mastcam-Z and RMI captured stones and boulders.

“We saw distinct layers in the escarpments containing rocks up to 5 feet [1.5 meters] through what we knew had nothing to do there, ”Mangold said.

These layers mean that the slow, winding waterway that fed into the delta had to be transformed by subsequent rapid flash floods. Mangold and the science team estimate that a torrent of water needed to carry the rocks – some for tens of kilometers – should move at speeds of 4 to 20 mph (6 to 30 km / h).

“These results also have an impact on the strategy for selecting rocks to sample,” said Sanjeev Gupta, Perseverance scientist at Imperial College London and co-author of the article. “The finest grained 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 taste old pieces of crustal rocks. Both are the main purposes of sampling and caching rocks before the samples return from Mars.

A lake of changing depths

Early in the history of the ancient Jezero crater lake, it is believed that its levels were high enough to reach the eastern edge of the crater, where orbital imagery shows the remains of an exit channel. The new document adds to that thinking, describing the size of Lake Jezero fluctuating dramatically over time, with its water level rising and falling several tens of meters before the body of water completely disappears.

While it is not known whether these water level fluctuations were the result of flooding or more gradual environmental changes, the science team determined that they occurred later in the history of the Jezero Delta, when the lake levels were at least 330 feet (100 meters) below the highest point of the lake. level. And the team is eager to do more information in the future: the delta will be the starting point for the rover team’s second upcoming science campaign next year.

“A better understanding of the Jezero Delta is essential for understanding the region’s hydrological change,” Gupta said, “and this could potentially provide valuable information on why the entire planet has dried up.”

Learn more about perseverance

A key focus of Perseverance’s mission to Mars is astrobiology, including looking 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 be the first mission to collect and cache Martian rock and regolith.

Subsequent NASA missions, in cooperation with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples on the surface and return them to Earth for further analysis.

The Mars 2020 Perseverance mission is part of NASA’s approach to exploring the Moon to Mars, which includes Artemis missions to the Moon that will help prepare for human exploration of the Red Planet.

JPL, which is managed for NASA by Caltech in Pasadena, Calif., built and manages the operations of the Perseverance rover.