Mars rover images show that Jezero Crater is an ancient Martian lake

The first scientific analysis of images taken by NASA’s Perseverance spacecraft now shows that the Jezero Crater (now a dry, wind-eroded depression) on Mars was once a calm lake with about 3.
7 billion A small river continuously provided water for it last year
.

The images also show evidence of flash floods in the crater
.

The power of this flood was enough to roll up the boulders dozens of miles upstream and deposit them on the lake bed, where these boulders are today

The new analysis, published today in the journal Science, is based on images of the rock outcropping the western part of the crater
.

Earlier satellite images showed that from above, the exposed rock resembled a river delta on the earth.

"If you look at these pictures, you are basically staring at this epic desert landscape
.

This is the most desolate place you may have been to," Professor of Planetary Science in the Department of Earth, Atmospheric and Planetary Sciences at MIT , Analysis team member Benjamin Weiss (Benjamin Weiss) said

"We now have the opportunity to find fossils," said team member Tanya Bossack, an associate professor of geobiology at MIT
.

"We hope to collect rock samples to find signs of life.

Tilted bed

On February 18, 2021, the lunar rover Perseverance landed at the bottom of Jezero Crater, just over a mile from its western fan-shaped outcrop
.

In the first three months, when NASA engineers performed remote inspections of many of the rover's instruments, the rover remained stationary

During this period, Perseverance’s two cameras, Mastcam-Z and the Super Camera Remote Micro Imager (RMI), took images of their surroundings, including remote photos of the edge of the outcrop and Kodiak Hill, planetary geology The authors speculate that a smaller outcrop may have been connected to the main fan-shaped outcrop, but was later partially eroded
.

Once the probe connects the image down to the earth, NASA’s "Perseverance" science team will process and combine the images and be able to observe different sceneries on the Kodiak hills with surprisingly high resolution.
Sediment bed
.

The researchers measured the thickness, slope, and lateral extent of each layer and found that the sediment must have been deposited by running water flowing into the lake, not by wind, flaky floods, or other geological processes

The rover also captured similar inclined sediment beds along the main outcrop
.

These images, together with Kodiak's images, confirm that the fan-shaped structure is indeed an ancient delta, and this delta is infused into an ancient Martian lake

Weiss said: "Without any driving, the rover can solve a huge unknown, that is, this crater was once a lake
.

" "Before we actually landed there and confirmed that it was a lake, this has been It's a problem

Boulder flow

When the researchers looked closely at the main image, they noticed large pebbles and pebbles on the topmost layer of the youngest delta
.
Some boulders are up to 1 meter in diameter and are estimated to weigh several tons
.
The research team concluded that these huge rocks must have come from outside the crater, most likely part of the bedrock at the edge of the crater or more than 40 miles upstream
.
Judging from their current location and size, the research team stated that these boulders were washed into the lake bed by a flow of water at a velocity of 9 meters per second and 3000 cubic meters per second
.
Weiss said: "You need energetic flood conditions to carry such large and heavy rocks
.
" "This is a special thing that may indicate a fundamental change in the local hydrology or regional climate on Mars
.
" These huge rocks are located.
The upper layers of the delta, they represent the most recently deposited material
.
These boulders are located on older, finer sedimentary layers
.
Researchers say this stratification suggests that for most of its existence, this ancient lake was filled by a slowly flowing river
.
Fine sediments—and possibly organic matter—flow down the current and settle into a gradually sloping delta
.
However, the crater later experienced a sudden flood, which deposited a large number of boulders on the delta
.
Once the lake dries up, after billions of years of wind erosion, the craters we see today are left behind
.
The reason for this climate change is unclear, although Weiss said the delta boulders may provide some answers
.
He said: "The most surprising result from these images is that we have the opportunity to capture the time when this crater transitioned from a habitable environment similar to the Earth to the desolate wasteland we are seeing now
.
" "These pebble beds may be a record of this transformation, and we haven't seen it elsewhere on Mars
.
"