NASA Study Finds Human-Associated Microbes Could Survive in the Moon’s South Polar Shadows

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Some microorganisms associated with humans and likely to accompany astronauts into space could survive in the permanently shadowed regions near the Moon’s south pole, according to NASA scientists.

The findings, published on August 19, 2026, in Science Advances, highlight the need to better understand how microbes persist in extreme lunar environments. As humans establish a longer-term presence on the Moon, it could become increasingly difficult to distinguish ancient lunar chemistry from contamination introduced by astronauts and spacecraft. The same concern will be critical during future missions to Mars.

“Humans are explorers of nature, and our voices, our memories, and our microbes are with us,” said Prabal Saxena, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who led the research. “For some scientists, including myself, that reality can be unsettling. But it also creates an opportunity to turn an imperfect situation into a useful experiment.”

Why microbial contamination matters on the Moon

Introducing microorganisms during human spaceflight is virtually unavoidable. Each area of human skin hosts large numbers of bacteria, and microbes can be released from spacesuits, habitats, equipment, and other systems used by astronauts.

The researchers warn that biological contamination could complicate the search for chemical clues about the Moon’s ancient geology and potential biological history. At the same time, they say the lunar south pole could serve as a natural laboratory for testing the limits of microbial survival in conditions that are difficult to reproduce on Earth.

Before extensive surface exploration begins, scientists will need baseline measurements of human-made pollutants and a detailed record of the Moon’s environment. These measurements could help researchers identify changes caused by future missions.

“We need to understand what came before us, because when we go to Mars to look for signs of life beyond our planet, we want to make sure it’s not something we brought with us,” said Andrew Needham, a co-author of the study and an Artemis lunar sample contamination-control scientist at NASA Goddard.

Microbes can be surprisingly resilient in space

Even strict sterilization procedures cannot eliminate every microorganism. One example is Aspergillus niger, a fungus commonly found in warm, damp environments such as bathrooms and heating, ventilation, and air-conditioning systems.

Astronauts have detected this fungus aboard the International Space Station, and experiments have shown that it can survive exposure outside the station. Because of its resilience in spaceflight environments, Aspergillus niger was included among the five microorganisms examined in the study, along with several bacteria and other fungi.

The ability of ordinary microorganisms to survive outside the International Space Station surprised scientists. These species are not generally classified as extremophiles, organisms specifically adapted to harsh conditions such as intense radiation, extreme dryness, or the vacuum of space, said Aaron Regberg, a geomicrobiologist at NASA’s Johnson Space Center in Houston and co-author of the study.

“We expected these microbes to be dry,” Regberg said.

NASA often heats robotic spacecraft to temperatures above 400 degrees Fahrenheit to reduce the number of microorganisms launched into space. However, such treatment cannot be applied to human astronauts. As a result, biological contamination presents a new challenge for crewed missions to the Moon’s south pole.

Permanent lunar shadows may protect microorganisms

To determine where microbes might survive, the researchers analyzed how sunlight and radiation affect the Moon’s polar regions. In this study, survival means that an organism remains alive for at least one day under simulated conditions. It does not mean that the microorganism can grow or reproduce.

The Moon has a very small axial tilt. From the lunar poles, the Sun appears to move just above the horizon, sending light across the surface at a shallow angle. Crater rims, mountains, ridges, and other elevated features can block that light from reaching lower areas.

These landforms create permanently or nearly permanently shadowed regions that remain extremely cold. Some may also contain water ice and other protected compounds. The lack of direct sunlight can reduce exposure to ultraviolet radiation, which is highly damaging to most microorganisms.

NASA models microbial survival near the lunar south pole

The research team studied microorganisms commonly associated with spaceflight environments and the human body. The organisms included Aspergillus niger, Bacillus subtilis, Staphylococcus aureus, Deinococcus radiodurans, and several Fusarium species.

Using results from previous laboratory studies, the scientists estimated the maximum levels of heat and ultraviolet radiation each organism could tolerate. They then modeled microbial survival in three areas near the Moon’s south pole: the Nobile Rim, the Connecting Ridge, and the De Gerlache Rim.

The simulations combined detailed elevation and temperature maps from NASA’s Lunar Reconnaissance Orbiter with models showing how solar radiation reaches the lunar surface. The resulting maps identified potential “survivable niches” ranging from the floor of a crater roughly a mile wide to an area as small as an astronaut’s footprint.

Aspergillus niger proved to be the most resistant to ultraviolet radiation among the organisms studied. The model indicated that it could potentially survive in locations exposed to limited sunlight. Ultraviolet radiation is highly lethal to many microorganisms and is widely used for sterilization in hospitals.

“When we think of the Moon, we don’t usually think of biology,” said Heather Graham, a NASA Goddard scientist and co-author of the study. Graham is helping develop tools and techniques capable of detecting biological systems that may differ significantly from those found on Earth.

“But because the Moon is a place where cells can survive, initial exploration of these sites should pay special attention to microbial hitchhikers and work diligently to characterize the Moon’s chemistry before a visit changes what we discover,” Graham said.

What the findings mean for future Moon and Mars missions

The researchers emphasize that the ability of some microorganisms to remain alive in shadowed lunar environments does not mean the Moon can support microbial growth. There is currently no evidence that the Moon contains all the conditions needed for reproduction, including stable liquid water, a moderate temperature, and a suitable atmosphere.

Instead, the study shows that some human-associated microbes may persist in dormant states after reaching the lunar surface. Understanding where and for how long they can survive will be essential for protecting lunar science, preventing forward contamination, and ensuring that future searches for life on Mars produce reliable results.