Could traces of life on Mars have survived until today? Scientists from NASA\u2019s Goddard Space Flight Center and Pennsylvania State University set out to answer that question. They conducted laboratory simulations of Martian conditions to examine how cosmic radiation affects the breakdown of biomolecules.<\/p>\n\n\n\n
The researchers placed E. coli<\/em> bacterial cells in solutions of pure water ice and, in a second set of samples, in ice mixed with materials typical of the Martian surface: silicate rock, dust, and clay. They cooled the samples to about \u221250 degrees Celsius, a temperature common in the icy regions of Mars. Next, they exposed them to gamma radiation equivalent to roughly 50 million years of radiation on the Martian surface<\/strong>. Afterward, the team analyzed the remaining amino acids.<\/p>\n\n\n\n The results revealed a clear difference. Amino acids preserved in pure ice degraded far more slowly than those mixed with Martian sediment<\/strong>. In samples containing only water ice, more than 10 percent of the amino acids from E. coli<\/em> survived the simulated 50 million years of exposure. In contrast, the samples containing ice mixed with Martian sediment degraded about 10 times faster and failed to preserve the molecules for such long periods.<\/p>\n\n\n\n 50 million years is significantly longer than the expected age of some current surface ice deposits on Mars, which are often less than 2 million years old, meaning that any organic life present in the ice would have been preserved. This means that if there are bacteria near the surface of Mars, future missions will be able to find them,<\/p>\n<\/blockquote>\n\n\n\n – emphasizes<\/a> study co-author Professor Christopher House.<\/p>\n\n\n\n The findings suggest that if microbes once lived in Martian permafrost or icy deposits, their chemical traces could still be detectable today with sufficiently sensitive instruments. At the same time, the study indicates that the traditional approach of examining rocks or dust on the Martian surface<\/a> may be less promising than scientists once believed. In those environments, organic molecules remain far more exposed to destructive radiation.<\/p>\n\n\n\n The authors therefore argue that future rovers and landers should focus primarily on regions dominated by ice or ice-rich permafrost. The search for life on Mars should target the polar caps and their edges, shallow ice deposits in the planet\u2019s mid-latitudes<\/strong>, and locations where earlier missions have already revealed ice just beneath a thin layer of sediment.<\/p>\n\n\n\n Locations with pure ice and permafrost with a predominance of ice should be the best places to search for amino acids on Mars, and thus represent a good target for future missions aimed at searching for traces of life,<\/p>\n<\/blockquote>\n\n\n\n – the researchers note.<\/p>\n\n\n\n The experiment did not focus solely on Mars. Scientists also examined how biomolecules degrade at temperatures typical of icy moons such as Europa, which orbits Jupiter, and Enceladus, a moon of Saturn. At these even lower temperatures, the rate of amino acid decomposition slowed dramatically.<\/strong><\/p>\n\n\n\n This is encouraging news for the Europa Clipper mission, which is currently traveling toward the Jovian system to investigate the icy crust and subsurface ocean of Europa. If ice on Mars can preserve traces of life on Mars for tens of millions of years, then the much colder ice on the moons of the outer planets could store such biological \u201ctime capsules\u201d<\/strong> for even longer.<\/p>\n\n\n\nIce Protects Life Better Than Rocks<\/h3>\n\n\n\n
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Life on Mars: Where Should We Look?<\/h2>\n\n\n\n
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The Colder It Is, the Greater the Chance of Success<\/h2>\n\n\n\n