Could Earth's toughest microbes survive for millions of years on Mars?

Science · Published 8 October 2026 Swipe more like this →

In short: While the Martian surface is a frozen, radiation-soaked desert, life might be hiding just beneath the dust. Recent experiments suggest that certain Earthly microbes could remain dormant for hundreds of millions of years, waiting for a splash of water to wake them up.

The search for life on Mars often focuses on its current harsh conditions: extremely low atmospheric pressure, intense ultraviolet radiation, and freezing temperatures. However, research led by Michael Daly and Brian Hoffman suggests that the planet's subsurface might offer a sanctuary. Researchers examined extremophile reactions to cosmic radiation, gamma rays, and high-energy protons by replicating Martian mid-latitude conditions, where temperatures drop to minus 80 degrees Fahrenheit (minus 63 degrees Celsius). The study specifically focused on the mid-latitudes of the Red Planet. These experiments also tested various fungi alongside several different types of bacteria.

One standout candidate is Deinococcus radiodurans, nicknamed "Conan the Bacterium," due to its ability to withstand radiation that would be lethal to almost any other known life-form. When bacteria and yeast are desiccated and frozen—similar to the freeze-drying process used for food—their resistance to radiation increases phenomenally. In these simulated Martian conditions, researchers estimated that such microbes could survive for up to 280 million years while lying dormant beneath the surface. This extreme resilience was observed when the organisms were subjected to solar ultraviolet light. Such conditions mimic the constant bombardment experienced by life forms on the Martian surface.

This discovery has significant implications for astrobiology. While Mars likely dried up about 3 billion years ago, the possibility that life could persist for much longer increases the chance of finding preserved evidence of past or present organisms. However, this also presents a challenge for planetary protection. If Earthly microbes contaminate the Martian surface, they could remain viable for hundreds of millions of years, making it nearly impossible to distinguish between indigenous Martian life and terrestrial contamination. This longevity could make it easier for scientists to locate preserved biological traces. However, it also raises concerns about the permanent nature of any accidental biological pollution.

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