NASA’s Curiosity rover has been shedding light on Mars since August 2011, making authentic discoveries on its surface, in your clouds and of course, about its potential habitability. And if its younger brother Perseverance found a few months ago “the clearest sign of life we have seen on Mars”, one of Curiosity’s latest discoveries is not so clear.
What Curiosity found. Since 2012, Curiosity has been exploring Gale Crater, a place where there was a lake billions of years ago. In March 2025, while the rover’s integrated laboratory was analyzing a clay rock there, they found the presence of decan, undecan and dodecan. What’s that? Alkanes, that is, long chain hydrocarbons formed by hydrogen and carbon atoms.
Why is it important. Because Curiosity’s discovery is the largest organic compounds ever found on the red planet and its size is such that its existence can hardly be explained by simple chemistry. On Earth, these types of hydrocarbons are usually fragments of fatty acids produced by living beings. However, on Mars, its origin is not so clear: it is reasonable to think of a biological origin, but with current evidence there is no confirmation.
Biology or geology? The degradation of fatty acids causes the appearance of these hydrocarbons one way or another, but their presence does not imply that they necessarily come from a living organism. In fact, on Earth they can also be generated by geological processes. In short: detecting organic molecules on Mars does not mean finding life. Correlation does not imply causation.
A “reasonable” hypothesis. So they analyzed the known non-biological sources of these organic molecules looking for an explanation for these quantities found. Since none of them fully explained this abundance, in this recent study published in Astrobiology that the research includes have raised a “reasonable” hypothesis: that living beings could have formed them.
Among the known sources are molecules from meteorites that crash into the surface of Mars, cosmic dust, geological chemistry such as the Fischer-Tropsch synthesis plausible on early Mars or ultraviolet radiation, which in addition to destroying organic components can also form them, are some of the candidates.
The method. To reach these conclusions, the team of scientists combined laboratory experiments, mathematical models and data from the rover, which allowed them to go back in time 80 million years to estimate how much organic matter existed at the beginning, before cosmic radiation destroyed it.
The amount they were able to reconstruct far exceeds what unknown non-biological processes can generate. Of course, it does not affirm that there was life, nor are there fossils or biomarkers of course. In fact, their conclusion is clear: more studies are needed to conclude on the absence or presence of life on Mars.
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Cover | NASA/JPL-Caltech/MSSS
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