As per a new NASA laboratory experiment, rovers may need to dig about 6.6 feet or more under the Martian surface to discover signs of ancient life because ionizing radiation from space degrades tiny molecules such as amino acids somewhat quickly.
Amino acids can be generated by life and by non-biological chemistry. Nonetheless, finding specific amino acids on Mars would be deemed as a potential indication of ancient Martian life because they are primarily used by terrestrial life as a component to manufacture proteins. Proteins are essential to life, as they are utilized to make enzymes that speed up or monitor chemical reactions and create structures.
“Our results suggest that amino acids are destroyed by cosmic rays in the Martian surface rocks and regolith at much faster rates than previously thought,” explained Alexander Pavlov of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Current Mars rover missions drill down to about two inches (around five centimeters). At those depths, it would take only 20 million years to destroy amino acids completely. The addition of perchlorates and water increases the rate of amino acid destruction even further.”
This outcome suggests a different search strategy for missions restricted to sampling at shallow depths. “Missions with shallow drill sampling have to seek recently exposed outcrops—e.g., recent microcraters with ages less than 10 million years or the material ejected from such craters,” explained Pavlov, lead author of a paper on this research published on June 24th in Astrobiology.