NASA’s Curiosity rover has detected long-chain alkanes –  a type of organic molecule, preserved within a Martian mudstone. The finding, published in Proceedings of the National Academy of Sciences, raises new questions about the possibility of past life or complex organic chemistry on the Red Planet.

The research team analyzed the mudstone from the Gale Crater, where Curiosity has been exploring since 2012. The presence of long-chain alkanes — organic molecules typically associated with biological processes — raises intriguing questions about the planet’s past environment. These hydrocarbons are significant because they are often produced by living organisms on Earth, suggesting that similar processes could have occurred on Mars.

Laboratory experiments support the hypothesis that the detected alkanes – decane, undecane and dodecane – were originally preserved in the mudstone as long-chain carboxylic acids. The fine-grained mudstone likely protected these organics from Mars’ harsh radiation, allowing them to survive billions of years. The origin of these molecules remains uncertain, as they could be derived from either abiotic or biological sources; however, their presence adds to growing evidence that Mars once had the right conditions to support organic chemistry, and possibly life as we know it now.

Researchers hope to uncover more organic-rich samples in the upcoming missions to piece together Mars’ ancient habitability.