NASA’s Perseverance rover explores secrets of ancient Martian lake

Now 1000 days later Marsthe mission traversed an ancient system of rivers and lakes, collecting valuable samples along the way.

On the occasion of the 1000th Martian day on the Red Planet, NASAThe Perseverance rover recently completed its exploration of an ancient river delta that holds evidence of a lake that filled Jezero Crater billions of years ago. The six-wheeled world has so far amassed a total of 23 samplesHe revealed the geological history of this region of Mars in the process.

Biological discoveries in Mars samples

One sample, called Liveroy Bay, contains a large amount of fine-grained silica, a substance known to preserve ancient fossils on Earth. The other Otis Peak contains a large amount of phosphate, which is often associated with life as we know it. Both samples are also rich in carbonates, which can preserve a record of environmental conditions since the rock formed.

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

This 360-degree mosaic of the “Airey Hill” site inside Jezero Crater was created using 993 individual images captured by the Perseverance Mars rover’s Mastcam-Z from November 3 to 6. The spacecraft remained parked at Airey Hill for several weeks during solar conjunction. Image source: NASA/JPL-Caltech/Arizona State University/MSSS

Geological history of Jezero Crater

“We chose Jezero Crater as a landing site because orbital images showed a delta — clear evidence that a large lake once filled the crater,” said Perseverance project scientist Ken Farley, of the California Institute of Technology. “The delta is a wonderful environment for burying signs of ancient life as fossils in the geological record.” “After comprehensive exploration, we pieced together the geological history of the crater, and charted the stage of the lake and river from beginning to end.”

Jezero was formed by an asteroid impact approximately 4 billion years ago. After the vehicle landed in February 2021, the mission team discovered that the floor of the crater was composed of igneous rocks formed from magma underground or from volcanic activity on the surface. They have since found sandstone and mudstone, indicating the first river reached the crater hundreds of millions of years later. Above these rocks there are mudstones rich in salts, indicating the presence of a shallow lake subject to evaporation. The team believes the lake eventually grew to be 22 miles (35 kilometers) in diameter and 100 feet (30 meters) deep.

This artist’s animated concept depicts water breaching the rim of Jezero Crater on Mars, which NASA’s Perseverance rover is now exploring. Water entered the crater billions of years ago, forming a lake, delta and rivers before the red planet dried up. Credit: NASA/Jet Propulsion Laboratory-California Institute of Technology

Later, fast-flowing waters carried rocks from outside Jezero Island, spreading them over the delta and elsewhere in the crater.

“We were able to see the outlines of these chapters in Jezero’s history in orbital images, but it took getting closer to Perseverance to understand the timeline in detail,” said Libby Ives, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory in the South. California, which runs the mission.

Attractive samples

The samples collected by Perseverance are the size of a classroom piece of 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).European Space Agency). Bringing the tubes to Earth would enable scientists to study samples using 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 erode a piece of potential rock and then studies the chemistry of the rocks using precision scientific instruments, including the Jet Propulsion Laboratory’s Planetary Instrument for X-ray Lithochemistry, or PIXL.

This image of Mars’ Jezero Crater is overlaid with mineral data detected from orbit. The green color represents carbonates – minerals that form in aquatic environments with conditions that may be suitable for preserving signs of ancient life. NASA’s Perseverance rover is currently exploring the green zone above the Jezero fan (center). Image source: NASA/JPL-Caltech/MSSS/JHU-APL

In a target the team called Bells Bay, PIXL observed carbonates — minerals that form in aquatic environments with conditions that may be suitable for preserving organic molecules. (Organic molecules are formed through geological and biological processes.) These rocks were also abundant in silica, an excellent material for preserving organic molecules, including those associated with life.

“On Earth, this fine-grained silica is what you often find in a site that was previously sandy,” said Morgan Keppel of JPL, deputy principal investigator at PIXL. “It is the environment in which, on Earth, the remains of ancient life can be preserved and later found.”

By analyzing this patch of eroded rock called Bells Bay, the PIXL instrument on NASA’s Perseverance Mars rover found that it is rich in carbonate (purple) and silica (green), both of which are good at preserving signs of ancient life. The image is overlaid with the chemical data of the device. Image source: NASA/JPL-Caltech/MSSS

Perseverance’s instruments are able to detect microscopic, fossil-like structures and chemical changes that may have been left behind by ancient microbes, but they have yet to see evidence of either.

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

After evaluating PIXL’s findings on each of these erosion patches, the team sent commands for the rover to collect nearby rock cores: Lefroy Bay was collected next to Bills Bay, and Otis Peak at Ouzel Falls.

PIXL, one of the instruments aboard NASA’s Perseverance Mars rover, analyzed the chemical composition of an area of ​​eroded rock dubbed “Ouzel Falls” and found that it is rich in minerals that contain phosphate, a substance found in the DNA and cell membranes of all life forms. known. Image source: NASA/JPL-Caltech/MSSS

“We have ideal conditions to find signs of ancient life as we find carbonates and phosphates, which indicate a habitable aquatic environment, as well as silica, which is great for preservation,” Keeble said.

The work of perseverance is, of course, far from complete. The mission’s fourth ongoing science expedition will explore the margin of Jezero Crater, near the mouth of the canyon where a river once flooded the crater floor. Rich carbonate deposits are observed along the margin, which stands out in orbital images like a ring within a bathtub.

More about the mission

The main goal of the Perseverance Mars mission is astrobiology, including the search for signs of ancient microbial life. The rover will describe the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and will be the first mission to collect and store Martian rocks and regolith (crushed rocks and dust).

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

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

JPL, which is managed by the California Institute of Technology for NASA in Pasadena, California, built and manages operations of the Perseverance rover.