In a little over a decade, samples of rover-scooped Mars Earth will rocket to Earth.
While scientists are eager to examine the Earth’s red planet for signs of life, scientists must consider a significant new challenge: Acid fluids – which once flowed on Mars ‘surface – may have destroyed biological evidence hidden within Mars’ iron-rich clay, according to researchers at Cornell University and the Spanish Centro de Astrobiología.
The scientists conducted simulations involving clay and amino acids to draw conclusions about the likely degradation of biological material on Mars. Their paper, “Limiting the Preservation of Organic Compounds in Mars’ Analog Nontronites After Exposure to Acid and Alkaline Liquids,” published September 15 in Nature Scientific reports.
Alberto G. Fairén, a visiting researcher at the Department of Astronomy at the College of Arts and Sciences in Cornell, is a similar author.
NASA’s endurance rover, launched on July 30, lands at Mars’ Jezero crater next February; The European Space Agency’s Rosalind Franklin rover will launch at the end of 2022. The Endurance Mission will collect Mars soil samples and send them to Earth by the 2030s. The Rosalind Franklin rover drills down to the surface of Mars, collects soil samples and analyzes them in situ.
In the search for life on Mars, the red planet’s clay surface soil is a preferred collection target, as clay protects the molecular organic material inside. However, the previous presence of acid on the surface may have compromised the clay’s ability to protect evidence of past lives.
“We know that acidic liquids have previously floated on the surface of Mars and altered the clay and its ability to protect organic matter,” Fairén said.
He said the clay’s internal structure is organized in layers where the evidence for biological life – such as lipids, nucleic acids, peptides and other biopolymers – can be captured and well preserved.
In the laboratory, the researchers simulated the surface conditions of Mars by aiming to preserve an amino acid called glycine in clay, which had previously been exposed to acidic liquids. “We used glycine because it could degrade quickly under the planet’s environmental conditions,” he said. “It’s the perfect informant to tell us what was going on inside our experiments.”
After a long exposure to Mars-like ultraviolet radiation, the experiments showed photodegradation of the glycine molecules embedded in the clay. Exposure to acidic liquids erases the interlayer space and turns it into a gel-like silica.
“When clay is exposed to acidic liquids, the layers collapse and the organic material cannot be preserved. They are destroyed,” Fairén said. “Our findings in this paper explain why searching for organic compounds on Mars is so very difficult.”
Photo: Mars rover revival
Carolina Gil-Lozano et al., Limiting the preservation of organic compounds in Mars analogous nontronites after exposure to acid and alkaline liquids, Scientific reports (2020). DOI: 10.1038 / s41598-020-71657-9
Provided by Cornell University
Citation: Study Shows Difficulty Finding Evidence of Life on Mars (2020, September 15) Retrieved September 15, 2020 from https://phys.org/news/2020-09-difficulty-evidence-life-mars.html
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