Fungus from NASA Cleanrooms Survives Simulated Mars Trip

A Stowaway in the Cleanroom

A fungus lurking inside NASA's ultra-sterile spacecraft assembly rooms could withstand the punishing conditions of a journey to Mars and persist on the planet's surface, according to new research published this week in Applied and Environmental Microbiology. The study is the first to demonstrate that a microbial eukaryote, a complex organism with a nucleus, could survive every phase of a Mars mission, from pre-launch preparation through space travel to robotic surface exploration.

Researchers led by microbiologist Kasthuri Venkateswaran, formerly of NASA's Jet Propulsion Laboratory Biotechnology and Planetary Protection Group, isolated 27 fungal strains from the assembly facilities used during the Mars 2020 programme, which delivered the Perseverance rover. Among them was Aspergillus calidoustus, a small filamentous fungus often found in plumbing and ventilation systems that had somehow persisted despite rigorous decontamination.

Only One Combination Proved Lethal

The team generated asexual reproductive spores, called conidia, and subjected them to simulated space and Martian stresses: ultraviolet and ionising radiation, near-vacuum atmospheric pressure, freezing temperatures, and exposure to Martian regolith. The conidia of A. calidoustus survived nearly every test. Only when extreme cold and high radiation were applied simultaneously did the fungus finally succumb, suggesting that survival depends not on resisting any single hazard but on an organism's combined stress-tolerance toolkit.

The finding underscores a gap in current planetary protection strategies, which have historically focused on resilient bacteria rather than fungi when evaluating germicidal techniques.

Implications for Planetary Protection

The study positions A. calidoustus as a leading candidate organism for testing and refining decontamination measures that guard against forward contamination, the inadvertent seeding of other worlds with Earth life. It arrives amid broader concern about microbial stowaways: late last year, a separate team identified 26 previously unknown bacterial species in NASA cleanrooms at Kennedy Space Center, many carrying genes for radiation resistance, biofilm formation, and spore production.

"This does not mean contamination of Mars is likely, but it helps us better quantify potential microbial survival risks," Venkateswaran said. "Microorganisms can possess extraordinary resilience to environmental stresses." Together, these investigations are helping refine NASA's planetary protection strategies and microbial risk assessment approaches for current and future space exploration missions.