Scientists find potential biosignature in Mars rock sampled by Perseverance
A leopard-spotted rock on Mars may, indeed, hold signs of ancient life.
Taking a new look at a very old mudstone on Mars, scientists believe they have found a potential biosignature, indicating that Mars may have once hosted life.
In July of 2024, while exploring an old, dried up river bed on the edge of Jezero Crater, NASA's Perseverance rover happened upon an odd-looking rock.
Subsequently named "Cheyava Falls" by the mission team, this ancient mudstone contained features that revealed it formed when water still flowed through the area.
NASA's Perseverance rover took this selfie at the 'Bright Angel' formation, after imaging and drilling into the rock known as 'Cheyava Falls' (just below image centre). The image is composed of hundreds of smaller pictures taken by the WATSON camera, located in the instrument cluster on the end of the rover's arm. (NASA/JPL-Caltech/MSSS)
Furthermore, close-up images revealed a wide stripe of material across it, which contained strange 'leopard spot' formations — small, dark, irregular rings, with lighter material inside them.
Shortly after the images and chemical analysis of the rock were transmitted back to Earth, the findings sent a ripple of excitement through the scientific community. The appearance of the 'leopard spots', along with the iron and phosphate found in the dark material in their borders, was very familiar.
Here on Earth, that same combination of features — rock 'bleached' from red to white, with iron and phosphate released in the process — results when certain microbes use chemical reactions to break down minerals, releasing energy that they consume to live.
While this wasn't a conclusive sign of past life on Mars, it was very intriguing, and over the past year, scientists delved deeper into the discovery.
A closeup view of Cheyava Falls, showing the olivine deposits and leopard spots that were of great interest to scientists back on Earth. (NASA/JPL-Caltech/MSSS/Scott Sutherland)
Now, new research has been published that verifies Cheyava Falls does contain potential biosignatures.
A biosignature is a chemical molecule, rock structure, etc, that could have formed due to biological life — in this case, past biological life.
This being a 'potential' biosignature simply means that the scientists are not absolutely sure yet that these structures and chemicals were definitely left behind by biological life. The evidence is compelling. However, there remains the possibility that what we're seeing in Cheyava Falls may be the result of some geological process, and more evidence is needed before those processes can be ruled out.
"These mudstones provide information about Mars' surface environmental conditions at a time hundreds of millions of years after the planet formed, and thus they can be seen as a great record of the planetary environment and habitability during that period," Joel Hurowitz, the lead author of the study, who is part of the Perseverance rover team at Stony Brook University, said in a press release.
"We will need to conduct broader research into both living and non-living processes that will help us to better understand the conditions under which the collection of minerals and organic phases in the Bright Angel formation were formed.”
Potential biosignatures have been spotted on Mars going back to the soil samples analyzed by the Viking landers in 1976. However, it takes a lot more to reach the conclusion that there was actually life there.
"Astrobiological claims, particularly those related to the potential discovery of past extraterrestrial life, require extraordinary evidence," Katie Stack Morgan, Perseverance’s project scientist at NASA’s Jet Propulsion Laboratory, said in a NASA press release. "Getting such a significant finding as a potential biosignature on Mars into a peer-reviewed publication is a crucial step in the scientific process because it ensures the rigor, validity, and significance of our results. And while abiotic explanations for what we see at Bright Angel are less likely given the paper's findings, we cannot rule them out."
According to Hurowitz and his study co-authors, to know for certain if they are seeing signs of ancient Martian life in these rocks, they need direct access to the sample that Perseverance drilled out of Cheyava Falls. As they wrote in their paper, the highly sensitive instruments available here on Earth will give them the measurements they need to make that determination.
Perseverance's samples as of July 24, 2025. The Sapphire Canyon sample is shown in the middle of the bottom row. (NASA/JPL-Caltech)
Unfortunately, that sample — named Sapphire Canyon — is currently being carried within the rover. So, it is millions of kilometres beyond their reach, and will need NASA to successfully conduct a Mars sample return mission to bring Sapphire Canyon here for study.