Ancient riverbeds on Mars and the possibility of life

NASA’s Curiosity Mars rover used two cameras to create this selfie in front of Monte Mercu, a 20-foot (6-meter) rocky outcrop. A new analysis by researchers at Penn State reveals that many of the craters found on Mars today could once have been habitable rivers. Image source: NASA/JPL-Caltech/MSSS

Results from the Curiosity rover indicate the presence of many craters Mars They may once have been flowing rivers, indicating possible conditions for ancient life.

New analysis of data from the Curiosity rover reveals that many of the craters on Mars today could once have been habitable rivers.

“We have found evidence that Mars was likely a planet of rivers,” said Benjamin Cardenas, assistant professor of Earth sciences at Penn State and lead author of a new paper announcing the discovery. “We see signs of this all over the planet.”

Corrosion simulation and results

In a study published in Geophysical Research LettersThe researchers used numerical models to simulate erosion on Mars over thousands of years, and found that the common crater formations — called seat-and-nose landforms — are most likely the remains of ancient riverbeds.

This study was the first to map the erosion of ancient Martian soil by training a computer model on a combination of satellite data, Curiosity images, and 3D scans of the strata — or layers of rock, called strata, that were deposited over millions of years — underneath. Sea floor in the Gulf of Mexico. The analysis revealed a new explanation for common Martian crater formations, which have never been associated with eroded river sediments until now.

Seat and slope morphology depicted on Mars and nose morphology from Earth in the Monte Mercu outcrop on Mars. Image source: NASA/Caltech-JPL/MSSS

“We have everything to learn about Mars by better understanding how these river deposits are interpreted stratigraphically, and by thinking of today’s rocks as layers of sediment that were deposited over time,” Cárdenas said. “This analysis is not a snapshot, but a record of change. What we see on Mars today are the remains of an active geological history, not some landscape frozen in time.”

Contradictory previous studies

Previous studies of satellite data from Mars have identified erosive landforms called fluvial ridges as potential candidates for ancient river deposits. Using data collected by the Curiosity spacecraft in Gale Crater, the team found signs of fluvial deposits not associated with fluvial ridges, but rather with landforms that have never been associated with ancient river deposits.

“This suggests that there may be undiscovered river deposits elsewhere on the planet, and that a larger portion of the Martian sedimentary record may have been built up by rivers during a habitable period of Martian history,” Cárdenas said. “On Earth, river corridors are very important for life, chemical cycles, nutrient cycles, sediment cycles. Everything indicates that these rivers behave similarly on Mars.”

Model design and ground comparisons

While designing their computer model, Cárdenas and his team discovered a new use for 25-year-old stratigraphy scans. Cardenas explained that surveys collected by oil companies under the seafloor in the Gulf of Mexico provided a perfect comparison to Mars.

The team simulated Mars-like erosion using 3D scans of actual layers recorded on Earth. When they ran the simulation, the model revealed an eroded Martian landscape that formed topographic benches and noses, rather than river ridges, and looked almost identical to the landforms observed by the Curiosity spacecraft inside Gale Crater.

“Our research suggests that Mars could have had many more rivers than previously thought, which certainly paints a more optimistic view of ancient life on Mars,” Cárdenas said. “It offers a vision of Mars where most of the planet once had conditions suitable for life.”

Reference: “Topography Associated with Exhumation of Alluvial Layers Filling Craters on Mars” by Benjamin T. Cardenas and Caitlin Stacy, August 8, 2023, Geophysical Research Letters.
doi: 10.1029/2023GL103618

The paper’s other co-author is Caitlin Stacy, a doctoral candidate in planetary earth sciences at Penn State. a NASA A Solar System Business Grant funded this work.