“Evidence of life”. Curiosity detects the largest organic molecules ever in Mars

Researchers who analyzed sprayed rocks aboard NASA’s Rover Curiosity have discovered the largest organic compounds on the red planet to date.

The discovery, last Monday in Proceedings of the National Academy of Sciences, suggests that prebiotic chemistry may have advanced more on Mars than previously observed.

The scientists analyzed a rock sample in the Curiosity Sam minillaries and found the molecules Dean, Undecano and Dodecano. It is thought that these substances, with 10, 11 and 12 carbon atoms, respectively, are the fragments of fatty acids that were preserved in the sample.

These fatty acids are among the organic molecules that, on our planet, are the Chemical Blocks of Life Construction.

Living beings produce fatty acids to help form cell membranes and perform various other functions. But fatty acids can also be produced lifeless, through reactions Chemicals triggered by various geological processes, including the interaction of mineral water in hydrothermal sources.

Although there is no way to confirm the origin of the identified molecules, their Discovery is exciting For Curiosity’s scientific team for several reasons.

Curiosity scientists small organic molecules had already discovered and simple in Mars, but the discovery of these larger substances provides the first evidence that organic chemistry has advanced to the type of complexity necessary for the Origin of Life on Mars.

The new study also increases the hypotheses that the large organic molecules that can only be produced in the presence of life, known as “bioassinaturas“They may be preserved on Mars, dissipating concerns that such compounds are destroyed after tens of millions of years of exposure to intense radiation and oxidation.

Scientists say that This discovery is a good omen For plans to bring Mars samples to Earth for analysis with the most sophisticated instruments available.

“Our study proves that, even today, through the analysis of Mars samples, we can detect past life chemical signatures, if it ever existed on Mars,” he said Caroline FreissinetA Principal Auto of Estudo E Investigadora No Latmos (Atmospheres Laboratory, Space Observations) do CNRS (National Center for Scientific Research) Em Guyancourt, França.

In 2015, Freissinet collided a team that, for the first time, conclusively identified Martian organic molecules in the same sample that was used for the current study. Nicknamed “Cumberland“The sample was analyzed several times with SAM, using different techniques.

Curiosity drilled the Cumberland sample in May 2013 in a gale crater area called “Yellowknife Bay“.

The scientists were so intrigued by Yellowknife Bay, who looked like an old lake bed, who sent Rover there before heading in the opposite direction to their main destination, Mount Sharp, which rises from the bottom of the crater.

The deviation was worth it: Cumberland is full of fascinating chemical clues about the past 3.7 billion of the gale crater. Scientists previously found that the sample is rich in clay minerals that form in water. It has sulfur in abundance, which can help preserve organic molecules.

Cumberland also has many nitrateswhich on Earth are essential for the health of plants and animals, and methane made with a type of carbon that is associated with biological processes on Earth.

Perhaps more important, scientists determined that Yellowknife Bay was, in fact,ocal of an old lakeproviding an environment that could concentrate organic molecules and preserve them in a thin grain sedimentary rock called Lamito.

“There is evidence that liquid water existed In the gale crater for millions of years and probably for much longer, which means that there was enough time for the life formation chemistry to occur in these environments of the Impact Crater Lake in Mars, ”he said Daniel Glavinsenior scientist for the delivery of samples at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, study co-author.

The recent discovery of organic substances It was a side effect From an un -related experience to probe Cumberland in search of signs of amino acids, which are the protein building blocks.

After warming the sample twice and measuring the mass of the released molecules, The team did not find evidence of amino acids. But they noticed that the sample released Small amounts of dean, Undecan and Dodecan.

Since these compounds may have been detached from larger molecules during warming, scientists worked in the opposite direction to find out what structures could have come. The hypothesis they raised was that these molecules were remnants of fatty acids – Undecanoic acid, dodecanoic acid and tridecanoic acid, respectively.

Scientists tested their forecast in the laboratorymixing Undecanoic acid in a clay similar to that of Mars and performing a similar experience to that of SAM. Once warm, Undecanoic acid released Deanas expected.

The investigators fthen a reference to experiences already published by other scientists to show that Undecan could have been separated from dodecanoic acid and the Dodecan from tridecanoic acid.

The authors found an additional intriguing detail in your studyrelated to the number of carbon atoms that constitute the acidic acid assumptions of the sample. The dorsal spine of each fat acid is a long and straight chain of 11 to 13 carbons, depending on the molecule. Non -biological processes produce Normally shorter fatty acidswith less than 12 carbon.

Cumberland sample may have longer chain fatty acids, scientists say, but SAM is not optimized to detect longer chains.

Scientists say that, ultimately, There is a limit for what can be inferred from “hunting” instruments of molecules that can be sent to Mars. “We are ready to take the next big step And bring samples from Mars to our laboratories to finally solve the life debate on Mars, ”said Glavin.