A Microbial Survival Model For The permanently Shadowed Regions Of The Moon Shows Long-Term Survival of Terrestrial Microbe Forward Contamination

Based on previous models of microbial survival there are regions in the solar system which have high preservation potential for terrestrial spore-forming microbes such as Bacillus subtilis.

Of these regions, only one is likely to be visited in the near future by human crewed spacecraft exploration: the permanently shadowed regions (PSRs) of the moon [3]. The lunar PSRs comprise an excellent protective niche for preserving viable microorganisms by largely removing two of the most important deleterious factors of the space environment: UV radiation and high temperatures.

This presentation will quantify these reductions to describe precisely how long viable microorganisms could persist in the PSRs. Our analysis suggests that exposure to the vacuum of space will be the largest contributing factor for most of the time required to reach a sterility assurance level (SAL), defined as a ‒12 log reduction in microbial viability.

Modelled rate of microbial survival for b. subtilis within two PSR craters. Primary UV radiation is the major cause of reduction out to between 4 and 5 years with vacuum exposure being the most deleterious factor thereafter. Total survival of viable spores in lit areas extends to between 30 and 31 years at a minimum with 47 years for sheltered areas of the crater floors. — 56th LPSC (2025)

A Microbial Survival Model For The permanently Shadowed Regions Of The Moon Shows Long-Term Survival of Terrestrial Microbe Forward Contamination, Abstract, 56th LPSC (2025)

Astrobiology,