The possibility that life existed on Mars billions of years ago has been confirmed.
An international research team led by Dr. Caroline Freissinet of the Sorbonne University in France announced on the 25th that the rover "Curiosity" discovered long-chain compounds with 10 to 12 carbon atoms connected in the Martian rock samples collected on Mars. The research findings were published that day in the Proceedings of the National Academy of Sciences (PNAS).
Curiosity is an exploration robot developed by the National Aeronautics and Space Administration (NASA) that has been conducting exploration missions since landing in Gale Crater on Mars in August 2012. The rock samples analyzed this time were collected in May 2013 from Yellowknife Bay in Gale Crater.
Curiosity drilled into the rock to collect a sample of Cumberland mudstone. This rock sample was analyzed in the Sample Analysis at Mars (SAM), a mini-laboratory mounted on Curiosity. Previously, when rock samples were analyzed in SAM, organic compounds with up to 6 carbon atoms had been discovered. This time, larger compounds were found.
The research team discovered molecules of decane, undecane, and dodecane, which are long-chain compounds with 10 to 12 carbon atoms consolidated in the rock samples. The team estimated that the compounds found in the samples could be remnants of fatty acids. Since living organisms produce fatty acids to form cell membranes and perform various functions, the presence of fatty acids could indicate traces of life.
Dr. Freissinet, who led the research, noted, "We have proven that we can find chemical signals showing that life existed on ancient Mars by analyzing rock samples." Yellowknife Bay, where Curiosity collected the rock samples, is a region where a lake likely existed in the past. The research team speculated that organic compounds were preserved in the fine sedimentary rocks of this area.
The research conducted this time originally aimed to focus on amino acids. Amino acids are the building blocks of proteins, which govern all life phenomena. The research team heated the rock samples in SAM to measure the mass of the molecules released in an effort to find direct evidence of amino acids, but no evidence of amino acids was found. Instead, a small amount of organic compounds was discovered.
The research team viewed the use of Curiosity's SAM for additional studies as limited. They explained that in the future, there is a need to bring Martian rock samples back to Earth for more precise analysis.
References
PNAS (2025), DOI: https://doi.org/10.1073/pnas.2420580122