The Moon has long been regarded as one of the most hostile environments in the solar system for life from Earth, with no breathable atmosphere, extreme temperature fluctuations and relentless exposure to space radiation and energetic particles. Yet new research led by NASA scientists suggests that some microorganisms carried inadvertently by astronauts or spacecraft could survive on the lunar surface for weeks or even months under certain environmental conditions, raising fresh concerns about the unintended transfer of terrestrial life beyond Earth.
The findings, based on an assessment of five forms of fungi and bacteria, indicate that the harsh lunar environment may not be uniformly lethal to all terrestrial microorganisms. Researchers used environmental simulations representing three regions near the Moon’s South Pole — Nobile Rim, Connecting Ridge and de Gerlache Rim — incorporating conditions derived from observations made by NASA’s Lunar Reconnaissance Orbiter as well as estimates of radiation exposure across the lunar surface. The results suggest that certain microorganisms could endure for significant periods in protected lunar environments, particularly inside permanently shadowed craters and during colder seasons such as autumn and winter.
The research has important implications for the rapidly expanding international effort to return humans to the Moon and establish a more sustained presence there. As astronauts, robotic systems, landers and other spacecraft travel between Earth and the lunar surface, microscopic organisms can potentially accompany them despite extensive cleaning and sterilization procedures. Such microorganisms could be transported through spacecraft interiors, equipment, spacesuits and other materials, creating a possibility that Earth-based life could inadvertently reach environments that have remained isolated from terrestrial biology for billions of years.
Among the organisms examined, the fungus Aspergillus niger emerged as the most resilient. Commonly known as a form of black mold, Aspergillus niger is widespread in warmer environments on Earth and is capable of growing in damp locations, including bathrooms and heating, ventilation and air-conditioning systems. Its ability to tolerate harsh conditions has also made it a recurring presence in human spaceflight environments. Astronauts have previously detected Aspergillus inside the International Space Station, while experiments have demonstrated that certain forms of the fungus can withstand exposure outside the station while in orbit.
NASA planetary scientist Prabal Saxena, the lead author of the study, said Aspergillus appeared particularly well suited to surviving in regions around the lunar poles, while species belonging to the Fusarium group also demonstrated considerable resilience. Fusarium is a common soil-borne fungus found across Earth and is known for its ability to persist in a variety of environmental conditions.
The researchers found that the two fungi studied were generally more resilient than the three bacterial species included in the assessment. However, survival was strongly dependent on location and environmental conditions. The Moon’s South Pole is of particular interest because permanently shadowed regions can remain extraordinarily cold and receive little or no direct sunlight, potentially creating localized environments where microorganisms shielded from extreme radiation could persist longer than previously assumed.
The study does not suggest that microorganisms would thrive and reproduce freely across the lunar surface. Instead, it indicates that some terrestrial microbes may remain viable for limited periods if they are placed in sufficiently favorable or protected conditions. That distinction is important because survival does not necessarily mean long-term growth or the establishment of a functioning ecosystem.
Nevertheless, the possibility of microbial survival has become increasingly significant as lunar exploration moves toward a new era. NASA and other space agencies are planning increasingly ambitious missions to the lunar surface, including efforts aimed at establishing sustained human activity and developing infrastructure around the Moon’s polar regions. With more spacecraft and people traveling to the lunar surface, the potential for biological contamination could increase substantially.
Scientists studying planetary protection have long sought to prevent Earth organisms from contaminating other worlds, particularly locations where conditions might theoretically support life. Such precautions are intended not only to preserve extraterrestrial environments but also to protect future scientific investigations. If terrestrial microorganisms were introduced into an unexplored environment and subsequently detected, researchers could face difficulty determining whether the organisms originated naturally or arrived from Earth aboard a spacecraft.
The new findings therefore add another layer to the scientific and policy debate surrounding lunar exploration. Although the Moon is generally considered an extremely hostile environment for biological activity, its diverse microenvironments — including permanently shadowed craters, subsurface areas and locations shielded from direct radiation — may provide temporary refuges for particularly resilient microorganisms.
The research also highlights the extraordinary adaptability of life on Earth. Fungi and bacteria have evolved to survive in environments ranging from deep underground and highly acidic waters to deserts, polar regions and spacecraft. Their resilience means that the boundaries of where terrestrial life can remain viable may be considerably broader than previously assumed.
For future lunar missions, the findings could reinforce the importance of strict spacecraft cleanliness, biological monitoring and planetary-protection protocols. Preventing microbial contamination may become especially challenging as missions transition from short-duration visits to repeated landings, permanent infrastructure and larger-scale human activity.
The Moon itself remains an inhospitable world for humans without sophisticated technology. But the new NASA-led research suggests that, at the microscopic level, Earth’s biological footprint could prove far more difficult to keep away. As humanity prepares to return to the lunar surface in increasingly ambitious missions, scientists may now have to consider not only how to protect astronauts from the Moon, but also how to protect the Moon from the microscopic passengers that accompany them.
