NASA's Curiosity rover has discovered the largest carbon-containing organic molecules ever found on Mars, a discovery that is one of the most important in the search for possible traces of ancient life on the Red Planet, Ars Technica reports.
The compounds identified may be fragments of fatty acids, which, in particular, are part of the membranes surrounding living cells.
Scientists suggest that if life ever existed on Mars, it was likely microbial. However, confirming this would require complex and bulky equipment that cannot be accommodated on a Mars rover.
Curiosity has discovered organic molecules, made up of long chains of carbon atoms with hydrogen and oxygen attached, in the 3.7-billion-year-old Cumberland rock, located on the likely dried-up lakebed in Gale Crater on Mars.
The Cumberland Rock was found in Yellowknife Bay, located in Gale Crater. This area contains rock formations similar to those formed from lakebed sediments. One of Curiosity's missions is to study whether past conditions on Mars could have supported life, and the lakebed is an ideal place for such studies.
Scientists have been searching for amino acids, the key building blocks of proteins and essential to life as we know it. But the unexpected discovery of large organic molecules has been just as exciting. The results of the study are published in the journal Proceedings of the National Academy of Sciences.
Among the molecules discovered were decane (with 10 carbon atoms and 22 hydrogen atoms) and dodecane (with 12 carbon atoms and 26 hydrogen atoms). These molecules belong to a group of hydrocarbons known as alkanes.
The researchers suggest that the alkanes molecules could have been building blocks of more complex fatty acid molecules. On Earth, fatty acids are the main components of fats and oils, and are formed through biological processes that contribute to the formation of cell membranes.
Alkane molecules are important for searching for biosignatures on Mars, but the exact mechanism of their formation remains unclear. They could have been formed through geological or other chemical processes unrelated to life, known as abiotic sources. However, the fact that these molecules have been preserved in samples that have been exposed to harsh environments for millions of years gives astrobiologists hope that evidence of ancient life can still be found today.