Spores from some fungi could survive the long trip to Mars, research in Applied and Environmental Microbiology reveals.
This is the first study to show that microbial eukaryotes – complex life forms with a membrane-bound nucleus – could persist through every part of a mission to Mars, from preparation to robotic exploration.
When space scientists send equipment into space, they think carefully about the risk of contaminating other worlds with microbes from our planet. Spacecraft components and equipment are thoroughly decontaminated in high tech cleanrooms, and to date, bacteria have been the main cause of concern.
In this study, however, researchers turned their attention to fungi. Aspergillus calidoustus is a small, filamentous fungus. It doesn’t produce mushrooms, which are the reproductive structures made by some other fungi, but it does make spores, tiny structures which enable it to reproduce asexually.
The fungus can be found in indoor environments, such as plumbing systems and ventilation systems. So, in 2020, when scientists were preparing to send to send the plucky Mars rover, Perseverance, on its way, they checked to see if the fungus was present in their high tech assembly rooms. It was.
Next, they wanted to find out how resilient the fungus was. Could it, for example, survive the journey to Mars if it inadvertently hitched a lift on the spacecraft?
So, they generated spores, known as conidia, from 27 of the fungal strains they found, and then subjected them to the intense conditions of space travel and Mars. This included exposing them to low temperature, ultraviolet and ionising radiation, low atmospheric pressure and Martian regolith, which is the loose, dusty rock material found on the planet’s surface.
No problem! The conidia tolerated these brutal conditions. “Microorganisms can possess extraordinary resilience to environmental stresses,” says Kasthuri Venkateswaran from the Biotechnology and Planetary Protection Group of NASA’s Jet Propulsion Laboratory. “This does not mean that contamination of Mars is likely, but it helps us better quantify potential microbial survival risks.”
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The team found that only the combination of extreme low temperature and high radiation could kill the fungus. This suggests that microbial survival is not determined by a single environmental stress but rather by combinations of mechanisms.
Last year, researchers discovered that spores from a particular moss were still viable after they spent nine months in space, touring the earth on the outside of the International Space Station. This shows that although microbial life may be tiny, we should never underestimate it.
Top image credit: DrPixel/Getty Images
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