A microscopic fungus discovered inside NASA clean rooms has raised fresh concerns about the possibility of Earth microbes contaminating other planets during space missions.
According to a new study published in the journal Applied and Environmental Microbiology researchers identified a highly resilient fungus called Aspergillus calidoustus inside spacecraft assembly facilities used during the Mars 2020 mission. Scientists say the organism was able to survive conditions similar to deep space travel and the harsh environment of Mars, exposing potential weaknesses in current planetary protection protocols.
The fungus was collected from clean rooms at Kennedy Space Center in Florida and Jet Propulsion Laboratory in California, highly controlled environments where spacecraft components, rovers, and landers are assembled under strict contamination prevention measures.
Researchers tested 27 fungal strains gathered from the facilities and found that the reproductive spores of Aspergillus calidoustus showed extraordinary durability. Nearly half the spores survived six months of intense radiation comparable to what spacecraft would experience during interplanetary travel. The fungus also endured two hours of dry heat at 257 degrees Fahrenheit, a sterilization process commonly used on spacecraft equipment.
Scientists further exposed the fungus to Mars-like conditions, including freezing temperatures, low atmospheric pressure, high solar radiation, and simulated Martian soil. The spores continued to survive under most scenarios, succumbing only when extreme cold and intense radiation were combined.
The findings are reigniting discussions about “planetary protection,” the international effort to prevent Earth organisms from contaminating celestial bodies during space exploration. Experts warn that accidental contamination could complicate the search for extraterrestrial life by making it difficult to determine whether detected microbes originated on another planet or were unknowingly carried from Earth.
“This is really about doing exploration responsibly,” microbiologist Atul M. Chander of the University of Mississippi told The New York Times. He explained that scientists want to ensure future missions do not transport hardy Earth microbes into environments being studied for ancient or present alien life.
The study also connects to growing scientific interest in extremophiles organisms capable of surviving in severe environments. Earlier this year, another study suggested that the radiation resistant bacterium Deinococcus radiodurans might survive being blasted from planets during asteroid impacts, supporting the theory known as lithopanspermia, which proposes that microbial life could travel between planets aboard rocky debris.
Former NASA planetary protection officer Cassie Conley said the findings reinforce a long-standing scientific reality that researchers still do not fully understand the survival limits of life on Earth. Speaking to Scientific American, she noted that some Earth organisms capable of surviving Martian conditions likely already exist.
Despite the alarming resilience of the fungus researchers emphasized there is no evidence that Earth fungi have reached Mars. Instead they say the discovery will help improve contamination prevention systems for future missions involving Mars, the Moon, and other potentially habitable worlds.
Study co-author Kasthuri Venkateswaran, a former microbiologist at NASA Jet Propulsion Laboratory, said the research would help refine microbial risk assessments and strengthen future planetary protection strategies as space exploration expands.
The discovery comes as global space agencies intensify efforts to search for signs of ancient microbial life on Mars, while also preparing ambitious human missions deeper into the solar system.