The Perseverance rover discovers evidence of catastrophic climate change in the distant past of Mars

according to MIT Press ReleaseThe first scientific analysis of images taken by NASA’s Perseverance rover has confirmed that Jezero Crater on Mars was once a calm lake, regularly fed by a small river about 3.7 billion years ago.

But the thin layers of clay and carbonate deposited in the fossil lake are covered in tar, a sedimentary rock made up of a mixture of large and small rocks. Scientists believe the rocks were captured tens of kilometers upstream and deposited in the ancient lake due to occasional flash floods, indicating catastrophic climate change in Mars’ distant past.

new analysis Published today in the magazine ScienceAnd They are based on images of rocks prominent on the western edge of the crater. Satellites had previously shown that this outcrop, seen from above, resembles river deltas on Earth., where layers of sediment settle into a fan as a river flows into a lake.

New images of the perseverance, taken from inside the crater, confirm that this outcrop was indeed a river delta. The rover’s cameras, the Mastcam-Z and SuperCam Remote Micro-Imager (RMI), captured images at a distance of 1.4 miles (~2.24 kilometers).

When the researchers took a closer look at images of the main outcrop, they noticed the large boulders and gravel embedded in the smaller and longer layers of the delta. Some of the rocks were up to 3 feet (1 meter) wide and weighed several tons. The team concluded that these massive rocks must have originated outside the crater and likely were part of bedrock at the crater rim or 40 or more miles upstream.

Judging from its current location and dimensions, the team says the rocks were carried downstream and to the bottom of the lake by rapid flooding of up to 9 meters per second and moved through 3,000 cubic meters of water. per second (like today). . Rain river in Europe).

The sedimentary succession indicates that the ancient crater Jezero Lake was fed for most of its existence from a gently flowing river. Then the climate became more extreme and flash floods deposited large boulders on the delta. After the lake dried up about 3 billion years ago, winds eroded the landscape, leaving the crater we see today. The cause of this climate change is not yet known.

“The most surprising thing that resulted from these images is the potential opportunity to capture the time as this crater passes from a habitable, Earth-like environment into this desolate landscape we see now,” he explains. Benjamin Weiss, Professor of Planetary Science in the Department of Earth, Atmospheric, and Planetary Sciences at MIT Member of the analysis team. “These rocks may be records of this transition, and we haven’t seen this anywhere else on Mars.”

Now that researchers have confirmed that the crater was once a lake environment, they believe its sediments may contain traces of ancient aquatic life.