Understand importance of organic molecules found in Mars

THE Rover Curiosity da NASA has detected the largest organic molecules ever found to date in Mars opening a window to the past of the red planet. Newly identified compounds suggest that a complex organic chemistry may have occurred in the past – the type necessary for the origin of life according to a new research.

The molecules, which include dean, Undecan and Dodecan, came to light after Rover analyzed a 3.7 billion -year -old rocked sample using its mini onboard laboratory called SAM (English for Sample Analysis at Mars – Mars sample analysis).

Scientists believe that the long chains of these molecules can be fragments of fatty acids – organic compounds that are essential chemical blocks for life on earth and help to form cell membranes. However, such substances can also be formed without the presence of life, arising from the interaction between water and minerals in hydrothermal sources.

Currently, it is not possible to confirm whether these molecules are evidence of life in Mars, but they add up to the growing list of compounds that robotic explorers have discovered on the planet in recent years. A study detailing the findings was published in the magazine Proceedings of the National Academy of Sciences.

The detection of these fragile molecules also animates astrobiologists, as it indicates that if there have already been biosinals (evidence of past life) in Mars, they can still be detectable – even with the intense solar radiation that has bombed the planet for tens of millions of years.

“If there was ancient life in Mars, she would have released some complex and fragile molecules,” said the main author of the study, Dr. Caroline Freissinet, scientist at the France National Center for Scientific Research, at the atmospheres laboratory, observations and space in Guyancourt. “And now that we know that Mars can preserve these molecules, it means that we could detect ancient life there.”

The discovery also reinforces the appeals to bring samples from Mars to Earth, where scientists could study them with more advanced tools and perhaps finally respond if life has existed outside our planet.

A discovery under construction for years

Curiosity landed in the Gale crater on August 6, 2012. More than 12 years later, Rover traveled more than 34 kilometers to climb Mount Sharp, which is inside the basin. The many layers of this formation preserve millions of years of Martian geological history, showing how the environment went from humid to dry.

Perhaps one of the most valuable samples Curiosity collected on its mission was obtained in May 2013. Rover drilled a rock called “Cumberland” in a region of the crater known as Yellowknife Bay, which resembled the bed of an old lake. The rocks intrigued the scientific team so much that Rover came back to collect samples before heading to Mount Sharp.

Since then, Curiosity has analyzed the Cumberland sample in various ways with SAM, revealing that Yellowknife Bay has housed an old lake, where clay minerals formed in water. The present leaflet there created an ideal environment to concentrate and preserve organic molecules, imprisoning them in the thin grains of the sedimentary rock.

Freissinet led a research team in 2015 that identified organic molecules in the Cumberland sample. The instrument has detected an abundance of sulfur (which helps preserve organic molecules), nitrates (essential for life on earth) and methane with a type of carbon associated with biological processes.

“There is evidence that liquid water existed in the Gale crater for millions of years, and probably much longer, which means that there was enough time for the chemistry necessary for the formation of life to occur in these lake environments,” said study co -author Daniel Glavin, a senior sample return scientist at Goddard Space Flight Center.

Curiosity preserved intact parts of the Cumberland sample in a “bag” so that Rover could revisit it later, even miles away from the original site. The team developed and tested innovative laboratory methods on Earth before sending commands to Rover to conduct new experiments with the sample.

In an attempt to verify the presence of amino acids (the protein blocks), the team instructed Sam to heat the sample twice. Despite not finding amino acids, the team made an unexpected discovery.

An intriguing detection

Scientists were surprised to detect small amounts of dean, Undecan and Dodecan, and performed reverse experiments on Earth to find out if these compounds could be residues of fatty acids: Undecanoic acid, dodecanoic acid and tridecanoic acid.

They mixed Undecanoic acid with a clay similar to that of Mars and warmed the mixture under conditions similar to those of Sam’s oven. The acid released dean – just as Curiosity detected.

Each remnant of identified fatty acid had between 11 and 13 carbon atoms. Anterior molecules found on Mars were smaller, with lower molecular weight and simpler structures.

“It is important to note that non -biological processes usually produce smaller fatty acids, with less than 12 carbons,” said Dr. Amy Williams co -author, an associate professor of geology at the University of Florida. “Larger and more complex molecules are probably necessary for the origin of life if it has occurred on Mars.”

Although the Cumberland sample may contain even longer chains, SAM is not designed to detect them. However, his ability to identify larger molecules suggests that he could detect life -related chemical signatures if they exist.

“Curiosity is not a life detection mission,” Freissinet explained. “It’s a mission to detect habitability – to know if the conditions were right for life to evolve. These results are at the limit of what Curiosity can do, and perhaps beyond what we expected.”

Before the missions, scientists thought it would be unlikely to find organic molecules in Mars, due to the intense radiation that reaches the planet for ages, said Glavin.

Although Curiosity does not return to Yellowknife Bay, there are still preserved samples on board. The team now plans a new experiment to see what else can be discovered. If they can identify similar long chain molecules, it will be another step towards understanding its origin.

“This is the most precious sample we have on board … waiting for the perfect experiment,” Freissinet said. “She keeps secrets-and we need to decipher them.”

Briony Horgan, Coinvestigator of the Mission of Rover Perseverance and professor of planetary science at the University of Purdue, called the discovery “a great victory for the entire team.” Horgan did not participate in the study.

“This detection really confirms our hopes that sediments deposited in old aquatic environments in Mars can preserve a true treasure of organic molecules, capable of telling us from prebiotic processes to possible biosignes of old organisms,” he said.

Dr. Ben Kd Pearce, assistant professor at the Department of Earth Sciences, Atmospheric and Planetary, Purdue University and Leader of the Research Laboratory in Origins and Astrobiology, called the discovery of “possibly the detection of more exciting organics to this day in Mars.” He also did not participate in the research.

Some scientists believe that fatty acids such as decanoic and dodecanoic formed the membranes of the first simple cell structures on Earth, Pearce said.

“This is the closest discovery we have ever had a significant biological signal-something possibly linked to the membrane structure, which is a fundamental feature of life,” Pearce said by email. “Organic molecules alone are intriguing, but not evidence of life. In contrast, biomolecules such as membranes, amino acids, nucleotides and sugars are central components of biology as we know, and finding any of them would be revolutionary (which has not yet occurred).”

The return of samples from Mars

The European Space Agency (ESA) plans to launch its Rover Exomars Rosalind Franklin in 2028, equipped with a complementary instrument to SAM. It can drill up to 2 meters below the surface of Mars, where it is more likely to find larger and better preserved organic molecules.

While Curiosity samples cannot be brought to Earth, Rover Perseverance is already collecting samples in Jezero Crater-an ancient river and lake delta-with the aim of sending them to Earth in the 1920s, through a complex series of missions called Mars Sample Return.

Both rovers have already detected organic molecules in various regions, suggesting that organic carbon is common in Mars, Williams said.

Nevertheless, their instruments cannot certainly determine the origin of these molecules, explained Dr. Ashley Murphy, a scientist at the Institute of Planetary Science. Murphy, who has already studied organic detected by Perseverance with Williams, did not participate in this new study.

“To properly investigate the issue of biosignes, these samples need high resolution analysis and sensitivity in terrestrial laboratories – which will only be possible when they are brought to Earth,” Murphy said.

If the Cumberland sample compounds are really by -products of microbial life from 3.7 billion years ago, it would coincide with the period when scientists believe that life began on Earth, according to Glavin. The discovery of Curiosity seems “so close” to answer this question, but the definitive answers must come from future analyzes here on Earth.

“I am more optimistic that we will finally be able to solve this debate about the existence of life on Mars – which seems to be open so long,” Glavin concluded.

Remember: NASA suggests existence of water reservoir on Mars

Water crystals found on Mars indicate life possibility

This content was originally published in Understand the importance of organic molecules found on Mars on CNN Brazil.

Source: CNN Brasil