NASA's Perseverance rover has confirmed the presence of organic carbon in two ancient Martian rocks from the Bright Angel formation within Jezero crater. The discovery, published in Science Advances, builds on Perseverance's September 2025 announcement of a potential biosignature in the same rocks.
Researchers used the SHERLOC instrument, mounted on Perseverance's robotic arm, to examine the rocks. SHERLOC employs Raman spectroscopy, which shines laser light onto material to identify minerals and organic compounds without damaging the rock. The measurements revealed macromolecular carbon (MMC), a form of carbon consisting of large, interconnected networks of carbon atoms. This material can form through biological activity or through nonbiological chemical processes, so its presence alone cannot confirm that Mars once hosted life.
The organic carbon was found only a few microns beneath the exposed Martian surface, the shallowest detection of macromolecular carbon ever reported on Mars. This location is striking because Mars' surface experiences radiation, sunlight, and chemically reactive substances that typically destroy organic molecules. Ashley Murphy, a postdoctoral researcher at the Planetary Science Institute and co-leader of the study, noted that the carbon "is either resistant to degradation and/or has been sufficiently shielded by other minerals, such as clays, or iron-rich Martian soil."
The surrounding geology indicates that water flowed through Jezero crater billions of years ago, depositing sediment that hardened into mudstone. The carbon was detected alongside carbonate and sulfate minerals that formed later as water altered the rocks, suggesting organic material may have entered or formed during at least two separate periods of Mars' geological history.
Perseverance collected the Bright Angel sample more than 2,000 miles from Gale Crater, where NASA's Curiosity rover previously detected organic compounds. Finding organic material at such widely separated locations suggests these compounds may once have been common across ancient Mars. Murphy stated this is "encouraging for Martian habitability," indicating that organics "may have been more widely available in ancient lakes and rivers on Mars."
Determining whether the rocks contain fossilized microorganisms remains beyond the capabilities of current rovers. The next step would involve examining Martian samples using laboratory equipment on Earth to reveal details too small or chemically subtle for rover instruments to resolve.