NASA researchers revealed on August 19, 2026, that common Earth microbes hitchhiking on crewed missions could survive for days or months in sheltered, shadowed areas near the Moon’s South Pole. Published in Science Advances, the findings raise significant planetary protection concerns for upcoming Artemis landings.
Microbial Hitchhikers and the Lunar Environment
When human explorers journey to the lunar surface, they bring along an invisible crew. On average, about 1 million bacteria live on a patch of human skin roughly the size of a pencil eraser, and these organisms inevitably escape from spacesuits and habitats into the surrounding environment Sciencedaily.
This reality complicates exploration efforts as space agencies prepare to return humans to the Moon for the first time since 1972. The primary concern is that Earth-born microorganisms could mix with native material, making it difficult for scientists to distinguish ancient lunar chemistry and native organic molecules from human-introduced contamination. Humans are natural explorers, and with them come their voices, their memories … and their microbes,
said Prabal Saxena, a planetary scientist who led the study from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
“Humans are natural explorers, and with them come their voices, their memories … and their microbes.”
Prabal Saxena, planetary scientist at NASA Goddard Space Flight Center
Saxena noted that while this realization can be unsettling for scientists, it also creates an opportunity to turn an imperfect situation into a useful experiment by studying the extreme limits of life. Before any surface science happens, researchers emphasize the need for a clear baseline of what biological contaminants humans bring along.
Why Lunar Shadows and Topography Matter
The Moon is generally an inhospitable place characterized by a lack of breathable air, extreme temperature swings, and relentless space radiation. However, the lunar south polar region presents a unique set of conditions. Because the Moon has a very small axial tilt, the Sun hovers just above the horizon, skimming the surface like a flashlight lying flat on a table.
This low sun angle means that crater rims, mountains, ridges, and even small surface bumps can block direct sunlight, creating permanently shadowed regions and localized pockets. These shadowed areas remain extremely cold, preserve water ice, and shield fragile molecules and potential microorganisms from direct ultraviolet radiation, which serves as the primary threat to microbes in these polar zones. By incorporating elevation and temperature data from the Lunar Reconnaissance Orbiter, researchers used models of how radiation strikes the surface to simulate surface conditions across three regions near the lunar South Pole: Nobile Rim, Connecting Ridge, and De Gerlache Rim.
The modeling demonstrated that scattered and reflected light still penetrates even shaded regions to some degree, but it leaves behind protected pockets where hardy organisms can persist.
Resilience of Aspergillus and Tested Microbes
To test survival limits, the team examined five common organisms frequently found in spaceflight environments, clean rooms, and on human skin: Aspergillus niger, Fusarium species, Deinococcus radiodurans, Staphylococcus aureus, and Bacillus subtilis. None of these organisms are traditionally classified as extremophiles capable of surviving the vacuum of space, making their persistence on the exterior of the International Space Station a surprise to investigators.
Among the tested candidates, the black mold fungus Aspergillus niger emerged as the clear champion. While the study evaluated survival rather than active growth or reproduction—defining survival as remaining alive for at least one Earth day—models showed that some niches may protect the hardiest organisms for a week or more, and potentially longer during lunar winter. By contrast, bacterial species such as Staphylococcus and Bacillus proved significantly more vulnerable to ultraviolet radiation.
As space agencies look toward establishing permanent lunar bases and eventually mounting missions to Mars, understanding these biological survival limits remains critical. We need to understand what was there before us, because when we go to Mars to search for signs of life beyond our planet, we will want to make sure it’s not stuff we brought,
said Andrew Needham, an Artemis contamination-control scientist for lunar samples at NASA Goddard.
