Explorers may have to dig about 6.6 feet (two meters) or more below the surface of Mars to find signs of ancient life, according to a new experiment in a NASA lab. ionizing radiation from space break down small molecules such as amino acids relatively quickly.
NASA’s Curiosity Mars rover took this selfie at a site nicknamed “Mary Anning” after a 19th-century British paleontologist. Curiosity captured three samples of rock drilled at the site. this site on the way out of Glen Torridon, where scientists believe it is a site where ancient conditions would have been favorable to support life, if it ever existed.
Vendor: NASA / JPL-Caltech / MSSS
Amino acids can be made by life and by non-biological chemistry. However, finding certain amino acids on Mars would be considered a potential sign of life on ancient Mars as they were widely used by terrestrial life as a building block. build proteins. Proteins are essential to life because they are used to make enzymes that speed or regulate chemical reactions and create structure.
“Our results show that amino acids are destroyed by cosmic rays in the Martian surface rock and regenerate at a rapid rate,” said Alexander Pavlov of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. much faster than previously thought. “Current Mars exploration missions drill down to about two inches (about five centimeters). At that depth, it only takes 20 million years to completely destroy the amino acids. The addition perchlorate and water accelerates amino acid destruction even further”. 20 million years is a relatively short time because scientists are looking for evidence of ancient life on the surface that was present billions of years ago when Mars was more like Earth.
This result suggests a new search strategy for tasks that are limited to sampling at shallow depths. Pavlov, the lead author of a article about this research published June 24 in the journal Astrobiology.
Cosmic rays are high-energy particles (mainly protons and helium ions) produced by powerful events on the Sun and in deep space, such as Solar radiation and exploding stars. They can degrade or destroy organic molecules when they penetrate meters (meters) into a solid rock, ionize and destroy everything in their path.
Earth’s thick atmosphere and global magnetic field shield the surface from most cosmic rays. When young, Mars also has these characteristics but loses protection as it ages. However, there is evidence that billions of years ago, a thicker atmosphere allowed liquid water to exist on the Red Planet’s surface. Since liquid water is essential for life, scientists want to know if life existed on Mars and look for evidence of life on ancient Mars by examining Martian rocks for signs of life. organic molecules such as amino acids.
The team mixed several amino acids in silica, hydrated silica, or silica, and perchlorate to simulate conditions in the Martian soil, and sealed the samples in a test tube under vacuum conditions to simulate thin air on Earth. Mars. Some samples were kept at room temperature, the warmest it has ever been on the Martian surface, while others were cooled to minus 67 degrees Fahrenheit (minus 55 degrees Celsius). The samples are detonated with different levels gamma radiation – a type of high-energy light – to simulate cosmic ray doses up to those obtained from about 80 million years of exposure in the Martian surface rock.
This is the first experiment to mix amino acids with simulated Martian soil. Previous experiments have examined gamma radiation on pure amino acid samples, but it is highly unlikely to find a large cluster of a single amino acid in a rock billions of years old.
“Our work is the first comprehensive study in which the destruction (radioactivity) of a wide range of amino acids has been studied under a variety of Mars-related factors (temperature, water content, etc.). , perchlorate abundance) and radiolysis rates were compared,” says. Pavlov. “It turned out that the addition of silicates and especially silicates to perchlorates significantly increased the rate of destruction of amino acids.”
While amino acids have not been found on Mars, they have discovered in meteorite, including one from Mars. “We have identified several straight-chain amino acids in the Martian Antarctic meteorite RBT 04262 in the Bioanalytical Laboratory at Goddard that we believe are of Martian origin (not pollution). from terrestrial biology), although the mechanism of formation of these amino acids is in RBT 04262 Danny Glavin, co-author of the paper at NASA Goddard, said. “Since Martian meteorites are typically ejected from depths of at least 3.3 feet (one meter) or more, it is possible that the amino acids in RBT 04262 were protected from cosmic radiation.”
Organic matter has been found on Mars by NASA Curiosity and Persist Walker; however, it is not a conclusive sign of life as it can be produced by abiotic chemistry. In addition, the results of the experiment imply that it is more likely that the organic matter observed by these rollers has been altered over time by radiation and is therefore not the same as when formed.
The research was funded by NASA under award number 80GSFC21M0002, 15-EXO15_2-0179 and NASA’s Planetary Science Division Internal Scientists Grant Program through the Basic Laboratory Research work package (FLaRe).
Source: NASA
