NASA Perseverance Mars Rover Images Confirm Jezero Crater Is an Ancient Martian Lake

Kodiak Butte Jezero Crater

Images from the Perseverance rover confirm that Jezero crater is an ancient Martian lake, researchers say. This Mastcam-Z enhanced color photo mosaic shows a butte near Jezero crater informally dubbed “Kodiak” by the rover team. Credit: NASA/JPL-Caltech/ASU/MSSS; edited by Jim Bell/ASU

The findings include signs of flash flooding that carried huge boulders downstream into the lakebed.

The first scientific analysis of images taken by

The new analysis, published on October 7, 2021, in the journal Science, is based on images of the outcropping rocks inside the crater on its western side. Satellites had previously shown that this outcrop, seen from above, resembled river deltas on Earth, where layers of sediment are deposited in the shape of a fan as the river feeds into a lake.

Perseverance’s new images, taken from inside the crater, confirm that this outcrop was indeed a river delta. Based on the sedimentary layers in the outcrop, it appears that the river delta fed into a lake that was calm for much of its existence, until a dramatic shift in climate triggered episodic flooding at or toward the end of the lake’s history.

Mars Jezero Crater Delta Scarp

This composite image of the “Delta Scarp” in Mars’ Jezero Crater was generated using data from two imagers aboard NASA’s Perseverance rover. Credit: RMI: NASA/JPL-Caltech/LANL/CNES/CNRS/ASU/MSSS

“If you look at these images, you’re basically staring at this epic desert landscape. It’s the most forlorn place you could ever visit,” says Benjamin Weiss, professor of planetary sciences in Mars Escarpment

Scientists believe the 377-foot-wide (115-meter-wide) escarpment is a portion of the remnants of a fan-shaped deposit of sediments that resulted from the confluence between an ancient river and an ancient lake. Credit: NASA/JPL-Caltech/LANL/CNES/CNRS/ASU/MSSS

Once the rover downlinked images to Earth, NASA’s Perseverance science team processed and combined the images, and were able to observe distinct beds of sediment along Kodiak butte in surprisingly high resolution. The researchers measured each layer’s thickness, slope, and lateral extent, finding that the sediment must have been deposited by flowing water into a lake, rather than by wind, sheet-like floods, or other geologic processes.

The rover also captured similar tilted sediment beds along the main outcrop. These images, together with those of Kodiak, confirm that the fan-shaped formation was indeed an ancient delta and that this delta fed into an ancient Martian lake.

“Without driving anywhere, the rover was able to solve one of the big unknowns, which was that this crater was once a lake,” Weiss says. “Until we actually landed there and confirmed it was a lake, it was always a question.”

Boulder flow

When the researchers took a closer look at images of the main outcrop, they noticed large boulders and cobbles embedded in the youngest, topmost layers of the delta. Some boulders measured as wide as 1 meter across, and were estimated to weigh up to several tons. These massive rocks, the team concluded, must have come from outside the crater, and was likely part of bedrock located on the crater rim or else 40 or more miles upstream.

Judging from their current location and dimensions, the team says the boulders were carried downstream and into the lakebed by a flash-flood that flowed up to 9 meters per second and moved up to 3,000 cubic meters of water per second.

“You need energetic flood conditions to carry rocks that big and heavy,” Weiss says. “It’s a special thing that may be indicative of a fundamental change in the local hydrology or perhaps the regional climate on Mars.”

Because the huge rocks lie in the upper layers of the delta, they represent the most recently deposited material. The boulders sit atop layers of older, much finer sediment. This stratification, the researchers say, indicates that for much of its existence, the ancient lake was filled by a gently flowing river. Fine sediments — and possibly organic material — drifted down the river, and settled into a gradual, sloping delta.

However, the crater later experienced sudden flash floods that deposited large boulders onto the delta. Once the lake dried up, and over billions of years wind eroded the landscape, leaving the crater we see today.

The cause of this climate turnaround is unknown, although Weiss says the delta’s boulders may hold some answers.

“The most surprising thing that’s come out of these images is the potential opportunity to catch the time when this crater transitioned from an Earth-like habitable environment, to this desolate landscape wasteland we see now,” he says. “These boulder beds may be records of this transition, and we haven’t seen this in other places on Mars.”

For more on this research, read NASA’s Mars Perseverance “Kodiak” Moment – Jezero Crater’s Lake Is More Complicated and Intriguing Than Thought.

Reference: “Perseverance rover reveals an ancient delta-lake system and flood deposits at Jezero crater, Mars” by N. Mangold, S. Gupta, O. Gasnault, G. Dromart, J. D. Tarnas, S. F. Sholes, B. Horgan, C. Quantin-Nataf, A. J. Brown, S. Le Mouélic, R. A. Yingst, J. F. Bell, O. Beyssac, T. Bosak, F. Calef III, B. L. Ehlmann, K. A. Farley, J. P. Grotzinger, K. Hickman-Lewis, S. Holm-Alwmark, L. C. Kah, J. Martinez-Frias, S. M. McLennan, S. Maurice, J. I. Nuñez, A. M. Ollila, P. Pilleri, J.W. Rice Jr., M. Rice, J. I. Simon, D. L. Shuster, K. M. Stack, V. Z. Sun, A. H. Treiman, B. P. Weiss, R. C. Wiens, A. J. Williams, N. R. Williams and K. H. Williford, 7 October 2021, Science.
DOI: 10.1126/science.abl4051

This research was supported, in part, by NASA.