Martian ice could preserve biomolecules for millions of years, lab study finds

Laboratory simulations and methods

Researchers froze bacterial samples and subjected them to conditions intended to mimic icy regions of Mars. Experiments used Escherichia coli cells embedded in two media: pure water ice and ice mixed with analogs of Martian soil such as silicate rock and clay. Samples were cooled to about -51°C and exposed to radiation levels representative of millions of years on the Martian surface.

Key findings

• Amino acids, the building blocks of proteins, persisted much longer in samples frozen in pure ice than in soil-containing ice.
• After exposure equivalent to roughly 50 million years on Mars, more than 10% of the original amino acids remained in the pure-ice samples; amino acids in soil-bearing samples were degraded almost completely.
• Tests at still lower temperatures—comparable to conditions on icy moons—showed further reductions in biomolecule breakdown rates.

Proposed preservation mechanism

The study suggests that in pure ice, radiation-generated reactive species such as free radicals become immobilized within the ice matrix, which limits secondary chemical reactions that would destroy biomolecules. By contrast, mineral components in soil analogs appear to create microenvironments that promote chemical pathways leading to faster molecular damage.

Implications for astrobiology and missions

These results indicate that ice-dominated deposits on Mars are especially promising places to search for preserved traces of past microbial life. The findings can inform mission planners when selecting landing sites and sampling strategies, prioritizing ice-rich locations and drilling or sampling approaches that access relatively uncontaminated ice layers.

Research context

Lead researchers noted that the experiments do not demonstrate past life on Mars but identify physical settings where biomolecular evidence would be most likely to survive for geologically long periods. Colder environments elsewhere in the solar system could offer even stronger preservation, increasing the scientific value of future exploration of icy worlds.

Bottom line: Pure ice can act as a long-term preservative for biomolecules under Martian-like temperature and radiation conditions, making polar and other ice-rich regions high-priority targets in the search for signs of former life.