The Perseverance rover discovers new evidence about water on Mars

(CNN) — After 1,000 days on Mars, NASA’s Perseverance rover has discovered new details about the history of an ancient lake and river delta on the Red Planet.

This new data, obtained through the rover’s painstaking field research, is helping scientists piece together Mars’ mysterious past and could ultimately determine whether or not life ever existed on the planet.

Perseverance and its helicopter companion Ingenuity landed in Jezero Crater on February 18, 2021 to search for signs of ancient microbial life.

As part of the research, the robotic explorer has just completed its search into a river delta that fed a lake that filled Jezero Crater billions of years ago. Along the way, Perseverance also collected 23 rock samples from various locations in the crater and delta.

Each sample, the size of classroom chalk and enclosed in metal tubes, could be returned to Earth in the future by a joint NASA/ESA Mars Sample Return Campaign. Studying samples on Earth will allow for more detailed analysis using laboratory equipment that is too heavy to be sent to Mars on board the rover.

On Tuesday, scientists participated in the fall meeting of the American Geophysical Union, held in San Francisco. Some conclusions Which they took from the Perseverance mission to Mars.

Tracking the trace of water on Mars

The rover collects samples using a scraper on its arm to scrape off Martian rocky surfaces, then analyzes the composition of the rocks using the Planetary X-ray Lithochemistry Instrument, known as PIXL.

Some of the rock samples recently obtained by Perseverance include silica, a fine-grained mineral that contributes to the preservation of ancient fossils and organic molecules on Earth. Organic molecules can form during geological and biological processes.

“On Earth, this fine-grained silica is what you often find in a sandy place,” Morgan Cable, deputy principal investigator for PIXL at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement. “It’s the kind of environment in which remnants of ancient life on Earth can be preserved and later found.”

Some of the rocks also contained iron bound to phosphate, a natural source of phosphorus, which acts as a component of DNA and cell membranes.

Carbonates were also detected in the samples. These minerals indicate past water-rich environments, and serve as time capsules of environmental conditions on Mars since rocks first formed.

“We chose Jezero Crater as a landing site because orbital images showed a delta, which is clear evidence that the crater was occupied by a large lake. The lake is a habitable environment, and the rocks of the delta are an ideal environment to bury signs of ancient life,” says Ken Farley, Perseverance project scientist and professor of chemistry. “After extensive exploration, we have reconstructed the geological history of the crater, tracing its lake and river phase from beginning to end.”

Mars rocks tell a story

Scientists believe that the Jezero crater was formed when an asteroid collided with Mars 4 billion years ago.

Perseverance began its mission by studying and sampling the crater floor shortly after landing. The rover’s detective work helped scientists determine that the crater’s floor is made up of volcanic rock formed by magma brought to the surface or volcanic activity on Mars.

As Perseverance progressed, the rover found examples of sandstone and mudstone, indicating that a river flowed into the crater millions of years after it was formed. All that remains is a top layer of salt-rich clay, indicating that a shallow lake filled the crater, becoming 35 kilometers wide and 30 meters deep, before some climate change caused the lake to evaporate.

Perseverance also found evidence of rocks from other places on Mars deposited in the river delta and in the crater by Fast flowing rivers.

“We were able to see these chapters in Jezero’s history broadly in orbital images, but it took getting closer to Perseverance to understand the chronology in detail,” said Libby Ives, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory.

This illustration shows water breaking over the rim of Jezero crater billions of years ago. The vehicle is now exploring the area. (Credit: JPL-Caltech/NASA)

Perseverance’s instrument suite has the ability to detect microscopic fossil structures and chemical signatures left by microbial life, but the rover detected neither. However, the geological evidence collected by the rover so far offers a very promising outlook.

“We have ideal conditions to find signs of ancient life, as we found carbonates and phosphates, which indicate an aquatic and habitable environment, as well as silica, which is well preserved,” Keeble explains.

The mission is not finished yet. The next step will be to study an area near the mouth of the crater, where a river has flooded the earth and left carbonate deposits resembling a bathtub ring.