NASA’s Perseverance rover explains the ancient history of Martian lakes

Marking its 1,000th Martian day on the Red Planet, NASA’s Perseverance rover recently completed its study of an ancient river that contains evidence of a lake that filled Jezero Crater billions of years ago. The six-wheeled scientist has so far collected a total of 23 examplesrevealing the history of this region of Mars in the process.

One sample called “Lefroy Bay” contains a large amount of fine-grained silica, a material known to preserve ancient fossils in the world. The other, “Otis Peak,” has a large amount of phosphate, which is often associated with life as we know it. These two samples are also rich in carbonate, which can preserve a record of the environmental conditions from the time the rock was formed.

The findings were shared on Tuesday, December 12, at the American Geophysical Union fall meeting in San Francisco.

“We chose Jezero Crater as the landing site because the satellite images showed a delta-clear evidence that a large lake filled the crater. in the geological record,” said the Perseverance project scientist, Ken Farley of Caltech. “After thorough research, we have compiled the history of the crater, mapping its lake and river from beginning to end.”

Jezero was formed from an asteroid impact nearly 4 billion years ago. After landing Perseverance in February 2021, the mission team discovered that the floor of the crater is made of limestone formed from magma underground or volcanic activity above. Since then they have found sandstone and mudstone, indicating the arrival of the first river two to one hundred million years later. Above these rocks are siltstones rich in salt, indicating the presence of a shallow lake. The team thinks the lake eventually grew as wide as 22 miles (35 kilometers) across and up to 100 feet (30 meters) deep.

Later, the water flowed and flowed from the rocks outside of Isero, spreading it over the valley and other parts of the crater.

“We were able to see a general outline of these chapters in the history of Jezero in the sequence of pictures, but it was necessary to get closer to the Passover to understand the timeline,” said Libby Ives, is a postdoctoral fellow at NASA’s Southern Jet Propulsion Laboratory. California, which controls the mission.

Attractive model

The samples collected by Perseverance are about the size of a classroom chalk and are stored in special metal containers as part of the Mars Sample Return campaign, a joint effort of NASA and the ESA (European Space Agency). Bringing the tubes to Earth will allow scientists to study samples with powerful instruments that are too big to take to Mars.

To decide which samples to collect, Perseverance first uses a probe to destroy a patch of a target rock and then analyzes the rock’s chemistry using precision science instruments, including JPL- built Planetary Instrument for X-ray Lithochemistry, or PIXL.

At the prospect the team calls “Bills Bay,” PIXL looked for carbonates—minerals that form in aquatic environments and conditions that might be good for preservation. organic molecules. (Organic molecules are formed by geological and biological processes.) These rocks were also rich in silica, which is an excellent material for preserving molecules. life support, including life support.

“On Earth, this fine silica you usually find in a place that used to be sandy,” said JPL’s Morgan Cable, PIXL’s principal investigator. “This is the kind of environment where, on the surface, the remains of ancient life can be preserved and found later.”

Perseverance’s instruments can detect all the particles, organic compounds and chemical changes that may have been left by ancient microbes, but they have never seen them. confirmation.

At another target explored by PIXL, called “Ouzel Falls,” the instrument detected the presence of iron associated with phosphate. Phosphate is part of the DNA and cellular structure of everything known on earth and is part of a molecule that helps cells carry energy.

After PIXL’s observations of each of these abrasion patches, the team issued instructions for the rover to collect rocks nearby. : Lefroy Bay collected near Bills Bay, and Otis Peak at Ouzel Falls.

“We have good conditions for finding signs of ancient life where we find carbonates and phosphates, which point to a water, living environment, as well as silica, which is very good in preservation ,” Cable said.

The work of perseverance, in fact, is very far. The mission’s ongoing science effort will explore the edge of Lake Jezero, near the entrance to the canyon where a river flooded the floor. the two. Most of the carbonate is deposited on the surface, standing out in continuous films like a ring in a bathtub.