Organic molecules of unprecedented size discovered on Mars

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Testbed instrument, a replica of SAM stored at NASA Goddard. This version is use
Testbed instrument, a replica of SAM stored at NASA Goddard. This version is used for preparation and verification of experiments taking place within its counterpart on Mars. © Caroline Freissinet
The longest organic molecules identified to date on Mars have recently been detected by scientists from the CNRS 1 , together with their colleagues from France, the United States of America, Mexico and Spain. These long carbon chains, containing up to 12 consecutive carbon atoms, could exhibit features similar to the fatty acids produced on Earth by biological activity 2 . The lack of geological activity and the cold, arid climate on Mars have helped preserve this invaluable organic matter in a clay-rich sample for the past 3.7 billion years. It therefore dates from the period during which life first emerged on Earth. These findings were published on March 24th 2025 in the journal PNAS .

he discovery was made using SAM 3 , co-funded by the French space agency CNES 4 . This is one of the instruments onboard NASA’s Curiosity rover, which has been studying the Gale crater on Mars since 2012. This success paves the way for future interplanetary science missions in search of signs of complex, life-like chemistry. This will be one of the goals of ESA’s upcoming ExoMars mission launched in 2028, and of the joint NASA-ESA Mars Sample Return mission in the 2030s. With an eye to exploration further out in the Solar System, the same international teams will build an instrument similar to SAM for Dragonfly , the drone that is due to explore the surface of Titan, Saturn’s largest satellite, from 2034 onwards.


    1 From the « Atmosphères et observations spatiales » laboratory (CNRS/Sorbonne Université/Université de Versailles Saint-Quentin-en-Yvelines/Université Paris Saclay).

    3 Built by a French-American team of scientists, Sample Analysis at Mars is a small laboratory within Curiosity ; its gas chromatograph and mass spectrometer allow it to identify molecules in collected samples.

Long-chain alkanes preserved in a martian mudstone

Caroline Freissinet*, Daniel P. Glavin, Paul D. Archer Jr., Samuel Teinturier, Arnaud Buch, Cyril Szopa, James M. T. Lewis, Amy J. Williams, Rafael Navarro-Gonzalez, Jason P. Dworkin, Heather. B. Franz, Maëva Millan, Jennifer L. Eigenbrode, R. E. Summons, Christopher H. House, Ross H. Williams, Andrew Steele, Ophélie McIntosh, Felipe Gómez, Benito Prats, Charles A. Malespin and Paul R. Mahaffy, PNAS , March 24th 2025, placeholder_lien_DOI