According to a new NASA laboratory experiment, rovers may have to dig more than six feet under the Martian surface to find signs of ancient life because ionizing radiation from space degrades small molecule such as amino acids very quickly.
Life and non-biological chemistry can be used to create mino acids. It would be considered a potential sign of ancient Martian life if it were found on the red planet. Life is dependent on the production of enzymes that speed up or regulate chemical reactions and on the creation of structures.
Alexander Pavlov of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said that the results suggest that the asteroids that hit Mars destroy the amino acids in the rocks. The current Mars rover missions drill down to about two inches. It would take 20 million years to destroy all of the acids. Adding perchlorates and water increase the rate of destruction. A period of 20 million years is a short amount of time because scientists are looking for evidence of ancient life on the surface that would have been present billions of years ago.
A new search strategy is suggested for missions that are limited to sampling. The lead author of a paper on this research said that missions with shallow drill sampling have to seek outcrops with ages less than 10 million years.
Powerful events on the sun and in deep space can cause Cosmic rays to be high-energy particles. When they penetrate yards into a solid rock, they can cause damage and destruction.
The surface of Earth is protected from most rays of the sun. Mars had these features when it was young, but lost them as it got older. Liquid water was able to persist on the surface of the Red Planet due to the thicker atmosphere. Since liquid water is essential for life, scientists want to know if life emerged on Mars, and look for evidence of ancient Martian life by examining Mars rocks.
The team sealed the samples in the test tubes under vacuum conditions to make sure they didn't leak. Some samples were kept at room temperature, which was the warmest on the surface of Mars, while others were chilled to a more typical minus 67 degrees. The samples were blasted with a type of highly energetic light that mimics the sound of a Cosmic Ray.
The experiment is the first of it's kind It's not likely to find a large group of a single amino acid in a billion-year-old rock.
"Our work is the first comprehensive study where the destruction of a broad range of amino acids was studied under a variety of Mars-relevant factors (temperature, water content, perchlorate abundance) and the rates of radiolysis were compared." Adding silicates and particularly silicates with perchlorates increases the rate of destruction of the amino acids.
One meteorite from Mars has been found with the discovery of the amino acids. Several straight-chain amino acids were identified in the meteorite, but the mechanism of their formation remains unclear. It is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556
It is not a conclusive sign of life since it could have been created by non-biological chemistry. The results of the experiment suggest that the organic material seen by these rovers has been altered over time by radiation and therefore not as it was when formed.
More information: Alexander A. Pavlov et al, Rapid Radiolytic Degradation of Amino Acids in the Martian Shallow Subsurface: Implications for the Search for Extinct Life, Astrobiology (2022). DOI: 10.1089/ast.2021.0166 Journal information: Astrobiology
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