Contamination risk on Moon! Human-related microbes may survive lunar South Pole — how Chandrayaan helped in new findings
A study published on 19 August 2026 in the journal Science Advances found that certain human-associated microorganisms could survive for at least one Earth day in the shaded, extremely cold regions of the Moon's South Pole.
The research, led by a planetary scientist at NASA's Goddard Space Flight Center, modelled five kinds of microorganisms that could plausibly hitch a ride with astronauts on upcoming crewed lunar missions.
"Survival" in the study meant the microbe stayed alive for at least a day, not that it could grow or reproduce in the lunar environment.
The findings raise contamination concerns for lunar exploration: distinguishing the Moon's natural chemistry from human-introduced biological material could become harder as crewed missions increase, with similar implications extended to future Mars exploration.
Data and terrain characterisation from lunar missions, including India's Chandrayaan missions, contributed to understanding of the shaded, cold micro-environments (permanently shadowed regions) at the lunar poles that the study focused on.
Planetary Protection and COSPAR Policy
Planetary protection refers to the practice of preventing biological contamination of celestial bodies by spacecraft/astronauts (forward contamination) and protecting Earth from any returned extraterrestrial material (back contamination). The international framework for this is set by the Committee on Space Research (COSPAR), which classifies missions into protection categories based on the target body and mission type.
Key Details
- COSPAR's Planetary Protection Policy assigns categories I through V; Category V specifically concerns protecting Earth from sample-return contamination.
- Lunar missions were traditionally classified under Category II (low risk), but COSPAR has since introduced sub-designations (IIa and IIb) specifically to address the scientific and human-exploration importance of the Moon's Permanently Shadowed Regions (PSRs) — the same shaded, extremely cold areas covered in this study.
- The updated lunar categorisation followed COSPAR's 2020-21 policy revisions responding to the anticipated increase in crewed missions to the lunar South Pole under NASA's Artemis programme.
The study's finding that microbes could survive in PSRs directly informs why COSPAR created finer-grained lunar sub-categories — the same shaded, cold "nooks and crannies" identified as scientifically valuable (for detecting water ice and pristine volatiles) are also the regions most vulnerable to biological contamination from human missions.
Permanently Shadowed Regions (PSRs) and Lunar South Pole Exploration
PSRs are craters near the lunar poles that never receive direct sunlight due to the Moon's near-zero axial tilt, keeping their floors at extremely low temperatures (below -170°C in places). These regions are of major scientific interest because they are believed to host water ice deposits, making them prime targets for both robotic missions and future crewed bases, including landing zones considered under the Artemis programme.
Key Details
- India's Chandrayaan-1 (2008) carried the Moon Impact Probe and instruments (including NASA's Moon Mineralogy Mapper) that contributed to the first strong evidence of water molecules on the lunar surface, including in polar regions.
- Chandrayaan-3 (2023) achieved a soft landing near the lunar South Pole (roughly 69°S), the first such landing in that region by any country, and its instruments studied surface composition and thermal properties.
- PSR floor temperatures can be cold enough to trap volatiles like water ice for billions of years, which is also what could make them hospitable to dormant microbial survival for short durations.
Chandrayaan data on lunar polar terrain and thermal conditions has fed into the broader scientific understanding of PSR environments that this NASA-led microbial survival study relies on, reflecting India's growing contribution to lunar South Pole science ahead of increased human exploration there.
Extremophiles and Astrobiology
Extremophiles are organisms capable of surviving extreme environmental conditions (temperature, radiation, vacuum, desiccation) that would be lethal to most terrestrial life. Studying such organisms informs both the search for life elsewhere in the solar system (astrobiology) and the risk of contaminating other worlds with Earth life (planetary protection), a foundational S&T theme for missions like Mars sample-return and lunar base planning.
Key Details
- The Science Advances study modelled microorganism survival based on radiation exposure, vacuum conditions, and temperature extremes typical of PSRs.
- Similar contamination-risk logic previously informed Mars mission protocols, since NASA's rovers and landers undergo strict sterilisation (bioburden reduction) before launch under COSPAR rules.
The study's authors explicitly extended their contamination concern beyond the Moon to Mars, tying this lunar finding to the same planetary protection logic long applied to Mars missions.
- Study published: 19 August 2026, in Science Advances.
- Number of microorganism types modelled: five.
- Survival threshold used in the study: at least one Earth day (not reproduction/growth).
- Lead researcher: a planetary scientist at NASA's Goddard Space Flight Center, Maryland.
- Chandrayaan-3 landing site: near the lunar South Pole (~69°S), landed 2023 — first South Pole soft landing by any nation.
- Chandrayaan-1 (2008) contributed early evidence of water molecules on the Moon via its Moon Impact Probe and onboard NASA instrument (Moon Mineralogy Mapper).
- COSPAR planetary protection categories: I to V, with new IIa/IIb sub-categories for lunar PSRs.