In 2004, the ESA mars express Orbiter methane detected in the atmosphere of Mars. Following this 2013 and 2014 when curiosity The rover detected methane spikes and organic molecules while exploring the floor of Gale Crater on Mars. curiosity detected Even bigger surge in 2019 While exploring a layered bedrock outcrop that is part of a larger geological formation known as ‘Teal Ridge’. Since then, scientists have been looking for: possible explanation Due to the sudden detection of this organic molecule, non-biological processes were generally favored.
In March 2025, Curiosity again detected small amounts of decane, undecane, and dodecane in rock samples, making up the largest organic compounds ever discovered on Mars. According to a new study published in the journal astrobiologyan international research team hypothesizes that these may be fragments of fatty acids preserved in the ancient mudstones of Gale Crater. If true, this would be the most convincing evidence yet that complex organic chemistry, and perhaps even life, once existed on Mars.
On Earth, carboxylic acids (also known as fatty acids) are natural byproducts of life and are found in seeds, nuts, and animal tissues. In animals, fatty acids are formed primarily from carbohydrates, primarily in the liver, adipose tissue, and mammary glands. However, abiotic and geological pathways leading to the formation of carboxylic acids are also known. These include lightning, hydrothermal activity in deep-sea vents, and photochemical reactions between ultraviolet light and hydrocarbon-rich mixtures.
*This diagram shows the long chain organic molecules decane, undecane, and dodecane. These are the largest organic molecules ever discovered on Mars. Credit: NASA/Dan Gallagher*
Complex organic molecules (COM) were detected in a drilled rock sample called “Cumberland”, Mars sample analysis (SAM) laboratory aboard the Curiosity rover. Because it was impossible to determine whether a molecule was created by a biological process based on SAM data alone, the researchers conducted a follow-up study to evaluate known non-biological sources. To do this, they needed to recreate what conditions were like at Gale Crater 80 million years ago, a period during which the rock would have been exposed at the surface.
This consisted of a combination of mathematical modeling of radiation experiments and Curiosity data. This allowed them to estimate how much organic material was present before it was destroyed by long-term exposure to cosmic radiation. This is far more than what typical non-biological processes can produce. The most likely source they thought was from carbonaceous meteorites, which are known to contain a variety of fatty acids that form in space. After their investigation, the researchers found that the non-living sources they considered could not fully explain the abundance of organic compounds detected by Curiosity.
This indicates that organisms may have formed these complex organic molecules (COMs), but the research team acknowledges that further research is needed. No conclusions about the existence of life can be drawn until scientists learn more about how quickly it decomposes under Mars-like conditions. In the meantime, these results could inform future astrobiological research on Mars and the much-awaited analysis of returned samples.
Read more: NASA