NASA study finds ancient life could survive 50 million years in Martian ice

Researchers from NASA Goddard Space Flight Center and Penn State recreated Mars like conditions in the laboratory to test that idea. They found that pieces of amino acids from E. coli bacteria, if trapped in Martian permafrost or ice caps, could survive more than 50 million years even under constant cosmic radiation. The findings, published in Astrobiology, suggest that missions searching for life on Mars should prioritize pure ice or ice rich permafrost instead of focusing mainly on rocks, clay, or soil.

"Fifty million years is far greater than the expected age for some current surface ice deposits on Mars, which are often less than two million years old, meaning any organic life present within the ice would be preserved," said co author 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. "That means if there are bacteria near the surface of Mars, future missions can find it."

Simulating Mars and Cosmic Radiation in the Lab

The study was led by Alexander Pavlov, a space scientist at NASA Goddard who completed a doctorate in geosciences at Penn State in 2001. The team sealed E. coli bacteria inside test tubes filled with pure water ice. Other samples were combined with water and materials commonly found 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 equivalent 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 additional 30 years of radiation exposure, bringing the total to 50 million years.

Pure Ice Protects Organic Molecules

The results were striking. In pure water ice, more than 10 percent of the amino acids, which are the building blocks of proteins, survived the full 50 million year simulation. By contrast, samples mixed with Mars like sediment broke down 10 times faster and did not survive.

A 2022 study by the same team had shown that amino acids preserved in a mixture 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 would be destroyed even more rapidly than the 10% water mixture," Pavlov said. "So, it was surprising to find 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 happen because a thin film forms where ice touches minerals. That layer could allow radiation to move more freely and damage amino acids.

"While in solid ice, harmful particles created by radiation get frozen in place and may not be able to reach organic compounds," Pavlov said. "These results suggest that pure ice or ice-dominated regions are an ideal place to look for recent biological material on Mars."

Implications for Europa and Enceladus

The team also tested organic material at temperatures similar to 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 will 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 reach Jupiter in 2030. The spacecraft will perform 49 close flybys to determine whether environments beneath the surface could support life.

Drilling Into Martian Ice

When it comes to Mars, accessing buried ice will require the right tools. The 2008 NASA Mars Phoenix mission was the first to dig down and photograph ice in the Martian equivalent of the Arctic Circle.

"There is a lot of ice on Mars, but most of it is just below the surface," House said. "Future missions need a large enough drill or a powerful scoop to access it, similar to the design and capabilities of Phoenix."

In addition to House and Pavlov, the research team included Zhidan Zhang, a retired lab technologist in the Penn State Department of Geosciences, along 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.