Space Stations Get Pretty Moldy. How Can We Prevent it?

Ask any property inspector, and they’ll tell you one of the maxims of their profession – where there’s moisture, there’s mold. That relationship also holds true for the International Space Station. The interior climate on the ISS is carefully controlled, but if thrown out of whack, potentially dangerous mold could sprout overnight. A new paper by researchers at The Ohio State University explains why – and provides some insights into how we might prevent it if it does happen.

The paper’s main finding was that dust collection, when exposed to moisture for only a short time, leads to a massive increase in the microbial population and a fundamental change in the dust itself to make it easier for the microbes to grow. There is plenty of dust on the ISS, so astronauts must be careful.

They already clean the screens covering the air filtration system on board regularly. The dust they collected from those screens formed the basis of the samples provided to Dr. Karen Dannemiller and her team at OSU. They separated the dust samples into different sub-samples and exposed each to a varying amount of moisture. Then, they watched as the microbes already present in the dust did their work.

A picture of mold growing on the ISS.
Credit – NASA

Dust is naturally created in the ISS from dead human skin and, of course, the microbes that live alongside us on a daily basis. However, in closed environments, an outbreak of bacteria would cause even more severe reactions than they do on Earth, including allergies and asthma. It is even possible that the dust and associated bacteria degrade the material structure of the ISS itself.

Running the collected samples through a higher moisture content is designed to mimic a possible failure on the ISS, such as an equipment malfunction. Knocking out an air ventilation fan in one part of the space station could create an environment similar to the one the dust is subjected to back on the ground.

So, what does that mean for our astronauts? For now, it’s best to understand where mold could form and keep up with cleaning schedules that allow them to nip it in the bud. There are several famous pictures of mold growing in a space station, so while generally successful, that has still been a known problem for a long time in space exploration. 

Bacteria were also found growing in the old Mir space station, as discussed in this Science Channel episode.
Credit – Science Channel YouTube Channel

Dr. Dannemiller and her colleagues have developed a model that could track mold growth in a closed environment like the ISS to combat this. They used data collected by analyzing the dust samples as part of their proof of concept for the software, but the eventual end goal is to predict where mold will grow before it begins and give the astronauts time to clean it out before it becomes a hazard. 

There will be plenty of space stations to work on this system in the future. Private spaceflight companies have become increasingly involved in developing space habitats, and NASA is setting up the ambitious Lunar Gateway to help with its Artemis missions to the moon. As more enclosed, sealed environments come online, it will be increasingly important to keep them free of these potentially dangerous microbial infestations. Experimenting with them and modeling that growth is one way to stay ahead of the curve.

Learn More:
Phys.org – Keeping mold out of future space stations
Nastasi et al – Predicting how varying moisture conditions impact the microbiome of dust collected from the International Space Station
UT – How Can Biofilms Help or Hinder Spaceflight?
UT – Earth’s toughest bacteria can survive unprotected in space for at least a year

Lead Image:
Scanning Electron Microscope image of dust from the ISS.
Credit – Microbiome / Nastasi et al.

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