NASA’s Curiosity rover has detected the largest organic molecules ever found on Mars — decane, undecane, and dodecane — suggesting that complex prebiotic chemistry may have occurred in the planet’s ancient lakebeds. The findings have been published in the Proceedings of the National Academy of Sciences. From a press release: Scientists probed an existing rock sample inside Curiosity’s Sample Analysis at Mars (SAM) mini-lab and found the molecules decane, undecane, and dodecane. These compounds, which are made up of 10, 11, and 12 carbons, respectively, are thought to be the fragments of fatty acids that were preserved in the sample. Fatty acids are among the organic molecules that on Earth are chemical building blocks of life. Living things produce fatty acids to help form cell membranes and perform various other functions. But fatty acids also can be made without life, through chemical reactions triggered by various geological processes, including the interaction of water with minerals in hydrothermal vents.
While there’s no way to confirm the source of the molecules identified, finding them at all is exciting for Curiosity’s science team for a couple of reasons. Curiosity scientists had previously discovered small, simple organic molecules on Mars, but finding these larger compounds provides the first evidence that organic chemistry advanced toward the kind of complexity required for an origin of life on Mars. The new study also increases the chances that large organic molecules that can be made only in the presence of life, known as “biosignatures,” could be preserved on Mars, allaying concerns that such compounds get destroyed after tens of millions of years of exposure to intense radiation and oxidation.
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