Moving a major step closer to proclaiming that life on Mars once existed, NASA researchers have discovered potential biosignatures in a sample collected last year by the Perseverance Mars rover, as announced in a new paper published in Nature.
Biosignatures are substances or structures that could have been produced by life, indicating a possibility that a planet was once inhabited, yet require more follow-up to prove the presence of life. The sample, “Sapphire Canyon,” was collected in the Jezero Crater, from a rock named “Cheyava Falls,” lying in a dry river bed on the Martian surface.
Exploring Bright Angel
While exploring an ancient river valley called the “Neretva Vallis,” nestled in the Jezero Crater, NASA tasked Perseverance with investigating a rocky outcrop named “Bright Angel.” Their analysis of the local rocks revealed the presence of clay and silt, excellent materials for preserving ancient microbial life, along with high amounts of organic carbon, sulfur, oxidized iron, and phosphorus.
“The combination of chemical compounds we found in the Bright Angel formation could have been a rich source of energy for microbial metabolisms,” said lead author Joel Hurowitz of Stony Brook University, New York. “But just because we saw all these compelling chemical signatures in the data didn’t mean we had a potential biosignature. We needed to analyze what that data could mean.”
During the exploration, the rover discovered the arrow-shaped Cheyava Falls in July 2024. Covered in colorful spots, the rock measures 3.2 by 2 feet. Those spots were of interest as potential signs that microbial life once used the carbon, sulfur, and phosphorus present as an energy source. The data on Cheyava Falls came from the PIXL instrument, used to take X-rays, and SHERLOC, which scans for organics and chemicals.
Tracing Biosignatures
High-resolution images collected by Perseverance more clearly displayed what researchers referred to as “leopard spots,” left from reaction fronts where chemical and physical reactions occurred. Beyond their strange appearance, the spots were interesting for their mineral signatures, correlating to vivianite and greigite. Both of these minerals have links to life on Earth, with vivianite commonly found in association with decaying matter and greigite produced by some varieties of microbial life.
Electron transfer between organic matter and the sediment left as a sign of past microbial life is the most likely explanation for the mineral traces, say the NASA researchers. However, it is not the only possible explanation. Adverse conditions such as acidic environments and enduring high temperatures could also produce the leopard spots, as well as the possibility of the presence of organic compounds without actual life. The reason the researchers suspect life as the most likely answer is the lack of other evidence in the rocks for acidic or high-temperature conditions, and uncertainty over whether the organic material would have been able to bind the minerals at such low temperatures.
Life on Mars
While finding biosignatures is exciting in and of itself, where they were found leads to a significant rethinking of scientists’ previous assumptions about any possible life on Mars. Cheyava Falls is among the youngest sedimentary rocks that Perseverance has yet analyzed. Researchers expected to find evidence of life only in much older rocks, suggesting a possible much later or much longer habitation window for life on Mars than previous estimates.
“Astrobiological claims, particularly those related to the potential discovery of past extraterrestrial life, require extraordinary evidence,” said Katie Stack Morgan, Perseverance’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California.
“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,” Morgan concluded.
Significant continued work will be necessary to follow up on the biosignature discovery, but it is a landmark in the search for extraterrestrial life.
The paper, “Redox-driven Mineral and Organic Associations in Jezero Crater, Mars,” appeared in Nature on September 10, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.