Microbes from Earth may survive on the moon, scientists find

Microbes from Earth May Survive in Lunar Shadows

Researchers analyzed three types of bacteria and two types of fungus commonly found on crewed space missions, such as Aspergillus niger. These organisms are resistant to extreme cold, vacuum, and high-energy particles. By comparing previously compiled survivability data with lunar maps containing ultraviolet and heat readings, scientists determined that both lunar poles likely host areas where microbes could persist in a dormant state known as cryptobiosis. In this state, the organisms cannot move or grow unless more hospitable conditions arise.

The Role of Permanently Shadowed Regions

The findings highlight the significance of permanently shadowed regions found inside large craters where the sun never climbs high in the sky. These areas can host ice and shield microorganisms from solar radiation and extreme heat. While temperatures in sunlighted areas can reach 130 degrees Fahrenheit (54 degrees Celsius), shadowed polar temperatures can plunge to –330 degrees Fahrenheit (about –201 degrees Celsius).

Survival in the study meant an organism could stay alive for at least one Earth day, though it does not imply the microbe can grow and reproduce. The research team tested simulations of three regions near the lunar south pole: Nobile Rim, Connecting Ridge, and De Gerlache Rim. These simulations used environmental maps built from elevation and temperature data collected by instruments aboard NASA’s NASA, combined with models of radiation strikes.

The fungi Aspergillus proved especially resilient in the models, persisting for up to seven Earth days in some shadowed regions due to thick walls and dark pigments protecting them from radiation. Even minimal disturbances could create habitable niches. Even a bootprint or a rover's tread may create a habitable area, study co-author Prabal Saxena, a planetary scientist at NASA Goddard Space Flight Center in Greenbelt, Maryland, told Space.com.

Implications for Artemis and Planetary Protection

As NASA prepares for crewed exploration, including plans to land humans near the lunar south pole, the risk of biological contamination becomes a central operational concern. Unlike robotic spacecraft, which NASA often bakes at temperatures above 400 degrees Fahrenheit to reduce living organisms, crewed missions inevitably transport millions of bacteria living on human skin that vent from spacesuits and habitats.

This contamination poses a challenge for scientists attempting to study native lunar chemistry and understand how the moon formed. Heather Graham, an organic geochemist at NASA Goddard Space Flight Center, noted that researchers want to ensure they are examining native materials rather than signals altered by human activity. Aaron Regberg, a geomicrobiologist at NASA’s Johnson Space Center in Houston who co-authored the paper, added that a clearer baseline measurement of astronaut-borne contaminants is needed before surface science can proceed.