Future missions to Mars will want to dig into ice somewhat than rock. Scientists say ancient microbes, or traces of them, may very well be locked inside Martian ice deposits, preserved for tens of hundreds of thousands of years.
Researchers from NASA Goddard Space Flight Center and Penn State recreated Mars like conditions within the laboratory to check that concept. They found that pieces of amino acids from E. coli bacteria, if trapped in Martian permafrost or ice caps, could survive greater than 50 million years even under constant cosmic radiation. The findings, published in Astrobiology, suggest that missions trying to find life on Mars should prioritize pure ice or ice wealthy permafrost as a substitute of focusing mainly on rocks, clay, or soil.
“Fifty million years is way greater than the expected age for some current surface ice deposits on Mars, which are sometimes lower than two million years old, meaning any organic life present inside the ice can be preserved,” said co writer Christopher House, professor of geosciences, affiliate of the Huck Institutes of the Life Sciences and the Earth and Environment Systems Institute, and director of the Penn State Consortium for Planetary and Exoplanetary Science and Technology. “Meaning if there are bacteria near the surface of Mars, future missions can find it.”
Simulating Mars and Cosmic Radiation within the Lab
The study was led by Alexander Pavlov, an area scientist at NASA Goddard who accomplished a doctorate in geosciences at Penn State in 2001. The team sealed E. coli bacteria inside test tubes full of pure water ice. Other samples were combined with water and materials commonly present in Martian sediment, including silicate based rocks and clay.
The frozen samples were placed in a gamma radiation chamber at Penn State’s Radiation Science and Engineering Center. The chamber was cooled to minus 60 degrees Fahrenheit to match temperatures in icy regions of Mars. The bacteria were then exposed to radiation corresponding to 20 million years of cosmic ray bombardment on the Martian surface. Afterward, the samples were vacuum sealed and shipped back to NASA Goddard under cold conditions for amino acid testing. Researchers then modeled an extra 30 years of radiation exposure, bringing the entire to 50 million years.
Pure Ice Protects Organic Molecules
The outcomes were striking. In pure water ice, greater than 10 percent of the amino acids, that are the constructing blocks of proteins, survived the complete 50 million 12 months simulation. Against this, samples mixed with Mars like sediment broke down 10 times faster and didn’t survive.
A 2022 study by the identical team had shown that amino acids preserved in a mix of 10% water ice and 90% Martian soil were destroyed more quickly than samples containing only sediment.
“Based on the 2022 study findings, it was thought that organic material in ice or water alone can be destroyed much more rapidly than the ten% water mixture,” Pavlov said. “So, it was surprising to search out that the organic materials placed in water ice alone are destroyed at a much slower rate than the samples containing water and soil.”
Researchers think the faster breakdown in mixed samples may occur because a skinny film forms where ice touches minerals. That layer could allow radiation to maneuver more freely and damage amino acids.
“While in solid ice, harmful particles created by radiation get frozen in place and will not give you the option to achieve organic compounds,” Pavlov said. “These results suggest that pure ice or ice-dominated regions are a really perfect place to search for recent biological material on Mars.”
Implications for Europa and Enceladus
The team also tested organic material at temperatures just like those on Europa, an icy moon of Jupiter, and Enceladus, an icy moon of Saturn. At those even colder temperatures, deterioration slowed down further.
Pavlov said the findings are encouraging for NASA’s Europa Clipper mission, which can study Europa’s ice shell and subsurface ocean. Europa is the fourth largest of Jupiter’s 95 moons. Europa Clipper launched in 2024 and is traveling 1.8 billion miles to achieve Jupiter in 2030. The spacecraft will perform 49 close flybys to find out whether environments beneath the surface could support life.
Drilling Into Martian Ice
With regards to Mars, accessing buried ice would require the precise tools. The 2008 NASA Mars Phoenix mission was the primary to dig down and photograph ice within the Martian equivalent of the Arctic Circle.
“There may be a whole lot of ice on Mars, but most of it’s slightly below the surface,” House said. “Future missions need a big enough drill or a robust scoop to access it, just like the design and capabilities of Phoenix.”
Along with House and Pavlov, the research team included Zhidan Zhang, a retired lab technologist within the Penn State Department of Geosciences, together with Hannah McLain, Kendra Farnsworth, Daniel Glavin, Jamie Elsila, and Jason Dworkin of NASA Goddard.
The work was funded by NASA’s Planetary Science Division Internal Scientist Funding Program through the Fundamental Laboratory Research work package at Goddard Space Flight Center.