Tracking Martian Organics with Gas Chromatography–Mass Spectrometry

In the past decade, scientists have made big strides in finding organic material on Mars, including simple carbon-based molecules in Gale Crater. A recent paper published in Nature Communications¹ reports how the Curiosity rover discovered more than 20 organic compounds in ancient, clay-rich rocks about 3.5 billion years old in an area called Gale Crater. Using various scientific techniques (including gas chromatography-mass spectrometry [GC-MS]), these molecules were released from the rocks through a chemical process and then identified, revealing a variety of carbon-based substances, including ones with similarities to those found in coal and petroleum on Earth.

Why are Scientists Studying Organic Materials on Mars?

Studying organic material on Mars is a key focus of today’s robotic missions, as space agencies use rovers and landers to learn whether Mars could have supported life in the past—or might still today—and to look for possible signs of it.² In just a decade, scientists have gone from simply looking for organic molecules on Mars to confirming that some in fact come from the planet itself. Now, in the opinion of the research team, the next step is figuring out where they came from—whether they were brought in from space by meteorites or dust or formed on Mars through natural processes or possibly even past life.

What Has the Curiosity Rover Discovered So Far in Places like Gale Crater?

Earlier findings from the Curiosity rover in Gale Crater have revealed a variety of organic compounds in Martian rocks, including chlorine-containing molecules, sulfur-rich compounds, and simple hydrocarbons—some of which may come from more complex, fatty-acid-like substances—showing that Mars contains a surprisingly diverse mix of carbon-based chemistry.^3-9

“We propose,” write the authors of the paper,¹ “that this suite of organics represents tetramethylammonium hydroxide (TMAH) thermochemolysis breakdown products from ancient organic macromolecular material that has been preserved in billions-of-years-old sedimentary rocks in Gale crater. Analysis of the spatial distribution of the organic matter is not possible with SAM (the Sample Analysis at Mars instrument suite onboard the Curiosity rover), therefore the origin of this material as being introduced from meteorites, abiotically produced via aqueous processing such as serpentinization or electrochemical production, is currently unknown.”

“Regardless,” the authors continue,¹ “confirmation of macromolecular organic matter supports the possibility that future optimized TMAH thermochemolysis experiments can liberate ancient biosignatures preserved in macromolecules on Mars (if present). The broad structural variety of organic molecules observed in situ from surface materials suggests some chemical diversity is preserved in ancient Martian sediments despite >3.5 billion years of diagenesis and radiation exposure. These results expand the library of confirmed and suggested organic molecules preserved over deep geologic time in the Martian near-surface and confirm the presence of macromolecular carbon on Mars.”

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References

1. Williams, A. J.; Eigenbrode, J. L.; Millan, M. et al. Diverse Organic Molecules on Mars Revealed by the First SAM TMAH Experiment. Nat Commun. 2026,17 (1), 2748. DOI: 10.1038/s41467-026-70656-0
2. Vasavada, A. R. Mission Overview and Scientific Contributions from the Mars Science Laboratory Curiosity Rover After Eight Years of Surface Operations. Space Sci Rev. 2022, 218 (3),14. DOI: 10.1007/s11214-022-00882-7
3. Mahaffy, P. R. et al. The Sample Analysis at Mars Investigation and Instrument Suite. Space Sci. Rev. 170, 401–478 (2012). DOI: 10.1007/s11214-012-9879-z
4. Freissinet, C. et al. Organic Molecules in the Sheepbed Mudstone, Gale Crater, Mars. J. Geophys. Res. 120, 495–514 (2015). DOI: 10.1002/2014JE004737
5. Szopa, C.; Freissinet, C.; Glavin, D. P. First Detections of Dichlorobenzene Isomers and Trichloromethylpropane from Organic Matter Indigenous to Mars Mudstone in Gale Crater, Mars: Results from the Sample Analysis at Mars Instrument Onboard the Curiosity Rover. Astrobiology 2020, 20 (2), 292-306. DOI: 10.1089/ast.2018.1908
6. Eigenbrode, J. L.; Summons, R. E.; Steele, A. et al. Organic Matter Preserved in 3-Billion-Year-Old Mudstones at Gale Crater, Mars. Science 2018, 360 (6393), 1096-1101. DOI: 10.1126/science.aas9185
7. Millan, M. et al. Sedimentary Organics in Glen Torridon, Gale Crater, Mars: Results from the SAM Instrument Suite and Supporting Laboratory Analyses. J. Geophys. Res. Planets 2022, 127, e2021JE007107 (2022). DOI: 10.1029/2021JE007107
8. Millan, M. et al. Organic Molecules Revealed in Mars’s Bagnold Dunes by Curiosity’s Derivatization Experiment. Nat. Astron. 2022, 6, 129–140 (2022). DOI: 10.1038/s41550-021-01507-9
9. Freissinet, C. et al. Long-Chain Alkanes Preserved in a Martian Mudstone. Proc. Natl. Acad. Sci. USA 2025, 122, e2420580122. DOI: 10.1073/pnas.2420580122