The acidic fluids, which once flowed over the Martian surface, would have destroyed the biological evidence hidden within the iron-rich clays from Mars.
This is a considerable new challenge for scientists studying the soils of the Red Planet for signs of life, warn researchers from Cornell and the Astrobiology Center of Spain.
The researchers performed simulations with clay and amino acids to draw conclusions about the probable degradation of the biological material on Mars.
He NASA Perseverance rover, launched on July 30, will land on the Jezero crater on Mars next February, while the The European Space Agency’s Rosalind Franklin rover will be launched in late 2022.
The Perseverance mission will collect Martian soil samples, which will return to the land by the 2030s on future missions.
The rover Rosalind franklin it will drill the Martian surface, collect soil samples and analyze them in situ.
In search of life in Mars, clay soils on the surface of the red planet 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 flowed on the surface of Mars in the past, altering clays and their ability to protect organics,” explains Alberto G. Fairén, visiting scientist at the Department of Astronomy, Cornell College of Arts and Sciences, corresponding author of the study.
In the lab, the researchers simulated conditions on the Martian surface with the goal of preserving an amino acid called glycine in the clay. that had previously been exposed to acidic fluids.
“We use glycine because it could degrade rapidly under the environmental conditions of the planet,” he said. “It is a perfect informant to tell us what was going on within our experiments.”
After long exposure to ultraviolet radiation similar to that of Mars, The experiments showed photodegradation of the glycine molecules embedded in the clay. Exposure to acidic fluids erases the interlayer space and turns it into a gel-like silica.