Molds are present in every human environment, including the International Space Station (ISS), with astronauts spending many hours a week ensuring the mold doesn’t grow to a size where it becomes a health problem. It is a sturdy life form that can withstand a lot of extremes. Now, recent research suggests it can also survive high doses of radiation, meaning its spores could exist on the outside of the ISS.
The research, presented at the 2019 Astrobiology Science Conference, showed that spores of Aspergillus and Penicillium (both found inside the ISS) can survive exposure to X-rays 200 times higher than the dose that would kill a human. Combined with their endurance to high temperatures, ultraviolet lights, chemicals, and dry conditions, they are extremely resilient.
“We now know that [fungal spores] resist radiation much more than we thought they would, to the point where we need to take them into consideration when we are cleaning spacecraft, inside and outside,” lead author Marta Cortesão, a microbiologist at the German Aerospace Center, said in a statement. “If we’re planning a long duration mission, we can plan on having these mold spores with us because probably they will survive the space travel.”
We already know that bacteria can survive long treks across space, hitching a ride on spacecraft. Now, it seems that mold can do the same. The researchers suggest updates to planetary protection protocols, which focus on the sterilization of spacecraft, that consider ways to get rid of mold spores.
In lab experiments, mold spores were exposed to 1,000 gray of X-rays and 500 gray of heavy ion bombardment. To put that in perspective, 0.5 gray is the threshold for radiation sickness and 5 gray is enough to kill a person. If a journey to Mars were to take 180 days, the cumulative dose of radiation would be 0.7 gray. That's water off a duck's back for the mold.
Cortesão points out that despite being dangerous in high quantities, mold can also be useful for the production of antibiotics and vitamins. They could be purposely employed on a long mission to produce compounds that may not come easy in space. To study these abilities in more detail, an experiment designed to test how molds grow in microgravity will launch in late 2019.