NASA’s Mars Perseverance rover deciphers the ancient history of the lake that filled Jezero Crater

On the occasion of his thousandth Martian day on the red planet Rover Perseverance NASA recently completed its exploration of an ancient river delta that preserves evidence of the presence of A Lago That filled Jezero Crater billions of years ago. So far, NASA’s “World of Six Wheels” has amassed a total 23 samples, Thus revealing the geological history of this region of Mars. A sample called “Lefroy Bay” contains a large amount of… good branch cutting, It is a material known for preserving ancient fossils on Earth. The other “Otis Peak” contains a large amount of phosphateWhich is often associated with life as we know it. Both samples are also rich in carbonates, which may retain traces of environmental conditions since the rock was formed.

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

“We chose Jezero Crater as the landing site because orbital images showed a delta, strong evidence that a large lake once filled the crater. The lake is a habitable environment, and the delta rocks are an excellent environment for burying signs of ancient life such as fossilssaid Perseverance project scientist Ken Farley of the California Institute of Technology. “After in-depth exploration, we reconstructed the geological history of the crater, tracing the stage of the lake and river from beginning to end..

Jezero was formed as a result of an asteroid impact approximately 4 billion years ago. After the rover landed in February 2021, the mission team discovered that the crater’s floor was made up of igneous rocks formed from underground magma or volcanic activity on the surface. They have since found sandstone and shale, indicating the first river reached the crater hundreds of millions of years later. Above these rocks are sandstones rich in salts, indicating the presence of a shallow, evaporating lake. The team believes the lake eventually grew to a diameter 35 km And depth 30 metres. Later, fast-flowing water carried rocks from outside Jezero, distributing them across the top of the delta and elsewhere in the crater.

“We’ve been able to see a big picture of these chapters of Jezero’s story in orbital images, but it took persistence to get close to truly understanding the timeline in detail.said Libby Ives, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory, which is managing the mission.

Attractive samples

The samples collected by Perseverance are about the size of a piece of blackboard chalk and are stored in special metal tubes as part of the Mars Sample Return campaign, a joint effort between NASA and the European Space Agency (ESA). Bringing the tubes to Earth would allow scientists to study samples with powerful laboratory equipment that is too large to be transported to Mars. To determine which samples to collect, Perseverance first uses a scraping tool to remove a piece of a potential rock and then studies the chemistry of the rocks using precise scientific instruments, including the Planetary X-ray Lithochemistry (PIXL) instrument made by JPL.

At a target the team calls “Bells Bay,” I spotted a PIXL carbonateThat is, minerals that form in aqueous environments with conditions that may be suitable for the preservation of organic molecules. Organic molecules are formed through geological and biological processes. These rocks were also rich in silica, an excellent material for preserving organic molecules, including those associated with life.

““On Earth, this fine-grained silica is often found in a place that was previously sandy.”said JPL’s Morgan Cable, PIXL’s deputy principal investigator. ““It is the environment in which, on Earth, the remains of ancient life can be preserved and later found.” Perseverance’s instruments can detect microscopic, fossil-like structures and chemical changes that may have been left behind by ancient microbes, but it has yet to find evidence of either.

In another target examined by PIXL, called “Ouzel Falls,” the device detected the presence of iron bound to phosphate. Phosphate is a component of the DNA and cell membranes of all known terrestrial life forms and is part of a molecule that helps cells transfer energy.

After evaluating the PIXL results in each of these erosion zones, the team sent commands to the rover to collect nearby rock samples: Lefroy Bay near Bills Bay and Otis Peak in Ouzel Falls were collected. “We have ideal conditions to find signs of ancient life as we find carbonates and phosphates, which indicate an aquatic and habitable environment, as well as silica, which is excellent for preservation.“Cable said.

But the work of perseverance is not over yet. The mission’s fourth ongoing science expedition will explore the rim of Jezero Crater, near the mouth of the canyon where a river once flooded the crater floor. Rich carbonate deposits are identified along the margin.