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The study shows difficulty in finding evidence of life on Mars

The study shows difficulty in finding evidence of life on Mars

NASA’s Perseverance rover, shown in this artistic rendition, will land at Mars’s Jezero Crater in February 2021 and begin collecting soil samples soon thereafter. Scientists are now concerned about acidic fluids that, once on Mars, may have ruined the evidence of life contained in the clays. Credit: NASA / JPL / Caltech / provided

In just over a decade, samples of Martian soil excavated by a rover will splash down to Earth.

While scientists are eager to study the red planet’s soils for signs of life, researchers must reflect on a new and considerable challenge: according to researchers from Cornell University and Spain’s Centro de Astrobiología.

The researchers conducted simulations involving clay and amino acids to draw conclusions about the likely degradation of biological material on Mars. Their article, “Constraining the Preservation of Organic Compounds in Mars Analog Nontronites After Exposure to Acid and Alkaline Fluids”, published September 15 in Nature Scientific reports.

Alberto G. Fairén, a visiting researcher in the Astronomy Department of the College of Arts and Sciences at Cornell, is a corresponding author.

NASA’s Perseverance rover, launched on July 30, will land at the Jezero crater of Mars next February; the European Space Agency’s Rosalind Franklin rover will be launched at the end of 2022. The Perseverance mission will collect samples of Martian soil and send them to Earth by 2030. The Rosalind Franklin rover will drill the Martian surface, collect soil samples and analyze them in Yes you.

In the search for life on Mars, the clay soils of the red planet’s surface are a preferred collection target as the clay protects the molecular organic material within. However, the past presence of acid on the surface may have compromised the clay’s ability to protect evidence of previous life.

“We know that acidic fluids have flowed to the surface of Mars in the past, altering the clays and its ability to protect organics,” Fairén said.

He said the clay’s internal structure is organized in layers, where evidence of biological life – such as lipids, nucleic acids, peptides and other biopolymers – can remain trapped and well preserved.

In the lab, the researchers simulated the conditions on the Martian surface by aiming to preserve an amino acid called glycine in the clay, which had previously been exposed to acidic fluids. “We used glycine because it could degrade rapidly based on the planet’s environmental conditions,” he said. “He’s a perfect informant to tell us what was going on in our experiments.”

After a long exposure to ultraviolet radiation from Mars, the experiments showed the photodegradation of the glycine molecules embedded in the clay. Exposure to acidic fluids clears the intercalary space, turning it into a gelatinous silica.

“When clays are exposed to acidic fluids, the layers collapse and the organic matter cannot be preserved. They are destroyed,” Fairén said. “Our findings in this paper explain why searching for organic compounds on Mars is so difficult.”

Image: revival of the Mars rover

More information:
Carolina Gil-Lozano et al, Limiting the storage of organic compounds in nontronite analogues of Mars after exposure to acidic and alkaline fluids, Scientific reports (2020). DOI: 10.1038 / s41598-020-71657-9

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Study Shows Difficulty Finding Evidence of Life on Mars (2020, September 15)
recovered on September 16, 2020
from https://phys.org/news/2020-09-difficulty-evidence-life-mars.html

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