DNA Fragments Could Survive In Martian Rocks For More Than 100 Million Years
The Centro de Astrobiología (CAB), CSIC-INTA, has led a study published in Communications Earth and Environment, showing that if life had ever emerged on Mars, DNA fragments could be preserved within its rocks for more than 100 million years, acting as biomarkers of past life.
The research, led by Dr. María-Paz Zorzano, was inspired by a key finding from the Curiosity rover, which detected organic carbon and simple organic molecules in 3.5-billion-year-old sedimentary rocks in Gale Crater, Mars. Analyses indicated that these rocks had remained buried for most of their history and were only exposed to cosmic radiation during the last 78 million years. Based on this observation, the team asked a fundamental question: Could DNA—a complex polymer containing life’s essential information and considered an unquestionable biomarker—survive the harsh Martian conditions?
To answer it, the researchers worked with a collection of terrestrial sedimentary rocks analogous to those on Mars, with organic carbon contents similar to those detected by Curiosity. These samples, from different geological environments, host unique microbiomes adapted to recycling the rock’s organic carbon and performing metabolic reactions based on the redox chemistry of minerals.
Using just half a gram of each sample, the team managed to extract and sequence hundreds of thousands of nucleobases through nanopore sequencing technology. The entire process was carried out in an ultra-clean room to avoid contamination. The rocks were also exposed to extreme doses of gamma radiation, equivalent to more than 100 million years of surface radiation on Mars.
The results were surprising: while small organic molecules such as amino acids or lipids degrade quickly under radiation, DNA—being a longer and more structured polymer—can retain recognizable fragments. Even after suffering breaks and irreversible radiological damage, between 1.5% and 8% of the DNA remained sequencable, and the analysis of these sequences enabled phylogenetic assignments. This demonstrates that such a molecule, essential for life, could preserve biological information even after millions of years of exposure to extreme Martian conditions.
The analysis also revealed that each type of rock hosted a characteristic microbiome: in some cases adapted to extremely arid environments, and in others characteristic of microorganisms that use iron.
This discovery comes at a key moment for Martian exploration. The Perseverance rover’s investigations in Jezero Crater have already identified rocks containing promising biomarkers. However, to definitively determine whether life ever existed on Mars, it will be necessary to bring these samples back to Earth—one of the main goals of NASA/ESA’s Mars Sample Return (MSR) missions and China’s Tianwen-3 mission.
“Our results reinforce the idea that DNA is one of the best candidates for detecting signs of life in extreme and planetary environments” says Dr. Zorzano. This work shows that, with current technologies, just half a gram of Martian rock would be sufficient to bring us one step closer to answering one of science’s most profound questions: Are we alone in the universe?
A — A microbialite ( ~ 2800-year-old) was sampled in Alchichica, Mexico, an alkaline crater lake with high concentrations of NaCl and Na₂CO₃. These microbialites formed through microbially mediated carbonate precipitation and remain submerged in shallow waters, where they continue to accrete carbonate minerals and support diverse microbial communities. B A stromatolite ( ~ 541 Ma) was sampled from this field in Morocco, which is part of the Mançour Group within the Ouarzazate Supergroup (Anti-Atlas region). This carbonate stromatolite formation (400 m × 500 m) developed in a shallow marine environment and was later buried beneath volcanic and volcaniclastic sediments. Tectonic uplift and erosion during the late Paleozoic and Cenozoic exposed the stromatolites, which are primarily composed of limestone (CaCO₃) and dolomite (CaMg(CO₃)₂), formed by cyanobacteria-driven sediment trapping and binding before the Cambrian explosion. C Carbonate samples ( ~ 2930 Ma) from drilled cores extracted from a depth of 133 m, in the carbonate formation from the Bridget Lake area. These samples consist of dolomite (CaMg(CO₃)₂). They precipitated in an open marine environment as dissolved calcium and bicarbonate ions reached saturation. Cyanobacteria likely influenced this process through photosynthesis, which removed CO₂, increased carbonate alkalinity, and promoted mineral precipitation. D Detailed view of a carbonate formation fragment ( ~ 2930 Ma). Small portions (4–5 g) were extracted from fragments of each sample type for further analysis. — Commun. Earth & Environ
Zorzano, MP., Basapathi Raghavendra, J., Carrizo, D. et al. Fragmented deoxyribonucleic acid could be extractable from Mars’s surface rocks, Commun. Earth & Environ. 6, 838 (2025). Doi: 10.1038/s43247-025-02809-w
Astrobiology
