If life ever existed on Mars, traces of it could still be frozen beneath the planet’s icy surface.
A new study from NASA and Penn State University suggests that fragments of biomolecules from ancient microbes could survive in Martian ice for tens of millions of years – long enough that future missions could potentially find them, according to a university statement.
In laboratory experiments simulating March Under these conditions, the researchers froze samples of E. coli bacteria in two different environments: pure water ice and a mixture of water and ingredients present in Martian soilincluding silicate-based rocks and clay. The samples were cooled to minus 60 degrees Fahrenheit (minus 51.1 degrees Celsius) – the temperature icy regions of Mars – then exposed to radiation levels equivalent to those they would experience on Mars for 20 million years. The results were extended through modeling to represent 50 million years of exposure, according to the release.
“Fifty million years is much larger than the expected age of some current ice deposits on Mars, which are often less than two million years old, meaning any organic life in the ice would be preserved,” said Christopher House, study co-author and professor of geosciences. the declaration. “This means that if there are bacteria near the surface of Mars, future missions will be able to find them.”
The researchers discovered that the amino acids – the building blocks of proteins – survived much better in pure ice than in ice mixed with sediment. More than 10% of the original amino acids remained intact after a simulated 50 million years of exposure, while those in the soil mixture degraded 10 times faster and did not survive. When tested at even colder temperatures, similar to those of European icy moon of Jupiter, and Enceladus, an icy moon of Saturn, the researchers found that this further reduced the rate of deterioration.
Therefore, the researchers suggest that in pure ice, radiation byproducts such as free radicals are trapped and immobilized, thereby slowing the chemical breakdown of biological molecules. On the other hand, the minerals present Martian soil appear to create thin films of liquid that allow destructive particles to move around and cause more damage.
“These results suggest that pure ice or ice-dominated regions are an ideal place to search for recent biological material on Mars,” Alexander Pavlov, lead author and space scientist at NASA’s Goddard Space Flight Center, said in the release.
This can help better plan areas to target during future missions to Mars and design tools capable of drilling in subsurface ice deposits – most of which are believed to be less than two million years old, meaning any biomolecular traces of a more recent habitable period could be preserved in the frozen ice.
Their conclusions were published on September 12 in the journal Astrobiology.