Mars organics may not be fully explained by non-biologic processes.

A study in Astrobiology examined large organic molecules (decane, undecane, dodecane) that Curiosity detected in Gale Crater and found that known non-biological sources could not fully account for their estimated original abundance; researchers say more work is needed before any conclusions about past life can be drawn.

Curiosity detected unusually large organic molecules in a Gale Crater rock sample in March 2025. The molecules — decane, undecane and dodecane — were found in a drilled sample called "Cumberland" and analyzed by the SAM laboratory. Earlier detections of methane and organics in Gale Crater and other Mars missions prompted further study. A new international study published in Astrobiology tested whether non-biological processes could explain the measured abundance. Key findings: - Past detections: Mars Express observed methane in 2004, and Curiosity recorded methane spikes and organics in 2013–2014 and a larger spike in 2019 at an outcrop linked to Teal Ridge. - March 2025 sample: Curiosity's SAM lab identified decane, undecane and dodecane in the Cumberland sample, the largest organic molecules detected on Mars to date. - Methods: Researchers combined radiation experiments and mathematical modeling with Curiosity data to estimate how much organic material would have survived roughly 80 million years of surface exposure. - Sources considered: The team evaluated non-biological pathways including delivery by carbonaceous meteorites, lightning, hydrothermal activity, and photochemical reactions, and found these could not fully explain the estimated original abundance. - Caution: The authors say a biological source remains possible but that current data do not permit a conclusion about past life until degradation rates under Mars-like conditions are better understood. Summary: The study raises the possibility that the detected complex organic molecules may exceed what known non-biological processes can produce, which could influence future astrobiology work and the analysis of returned samples. Undetermined at this time.