Performance Testing of a Photocatalytic Oxidation Module for Spacecraft Cabin Atmosphere Revitalization

Perry, Jay L.; Abney, Morgan B.; Frederick, Kenneth R.; Scott, Joseph P.; Kaiser, Mark J.; Seminara, Gary; Bershitsky, Alex

doi:10.2514/6.2011-5236

Cited by 1 publication

(1 citation statement)

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“…22 In addition, capture of bacterial-and fungal-related airborne particles is a major function of the ISS air filtration system. 23 Increased levels of relative humidity facilitate rapid microbial growth, especially for fungi. Elevated equilibrium relative humidity (ERH) in the air is sufficient to provide enough water availability to microbes to support growth in the dust 8,24,25 , which can be predicted even under varying relative humidity conditions using the time-of-wetness framework.…”

Section: Introductionmentioning

confidence: 99%

Predicting how varying moisture conditions impact the microbiome of dust collected from the International Space Station

Nastasi,

Bope,

Meyer

et al. 2024

Preprint

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Background The commercialization of space travel will soon lead to many more people living and working in unique built environments similar to the International Space Station, which is a specialized closed environment that contains its own indoor microbiome. Unintended microbial growth can occur in this environment as in building on Earth from elevated moisture, such as from a temporary ventilation system failure. This growth can drive negative health outcomes and degrade building materials. We need a predictive approach for modeling microbial growth in these critical indoor spaces. Results Here we demonstrate that even short exposures to varying elevated relative humidity can facilitate rapid microbial growth and microbial community composition changes in dust from spacecraft. We modeled fungal growth in dust from the International Space Station using the time-of-wetness framework with activation and deactivation limited growth occurring at 85% and 100% relative humidity, respectively. Fungal concentrations ranged from an average of 4.4 x 106 spore equivalents per mg dust in original dust with no exposure to relative humidity to up to 2.1 x 1010 when exposed to 100% relative humidity for 2-weeks. As relative humidity and time elevated increased, fungal diversity was significantly reduced for both alpha (Q < 0.05) and beta (R2 = 0.307, P = 0.001) diversity metrics. Bacteria were unable to be modeled using the time-of-wetness framework. However, bacterial communities did changes based on constant relative humidity incubations for both beta (R2 = 0.22, P = 0.001) and alpha diversity decreasing with increasing moisture starting at 85% relative humidity (Q < 0.05). Conclusion Our results demonstrate moisture conditions can be used to develop predict changes in fungal growth and composition onboard human-occupied spacecraft. This predictive model can be expanded upon to include other spacecraft environmental factors such as microgravity, elevated carbon dioxide conditions, and radiation exposure. Understanding microbial growth in spacecraft can help better protect astronaut health, fortify spacecraft integrity, and promote planetary protection as human activity increases in low-Earth orbit, the moon, Mars, and beyond.

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