Microbial detection and control on the International Space Station

The International Space Station (ISS) is a semi-closed and complex microbial ecosystem, occasionally altered by periodic additions of microbiota from Earth. As the habitable volume of the ISS is closely shared between its human and microbial inhabitants, numerous and stringent levels of microbial control are in place to minimize risk to crew health and vehicle performance. Preventative efforts begin during vehicle design and include evaluations leading to suitable materials selection, measures to reduce humidity and eliminate free water, and means to maintain high-volume air flow and filtration. Continuing this preventative approach, spaceflight food and cargo is microbiologically monitored prior to flight and must meet stringent acceptability limits. In addition, crewmembers also receive preflight medical examinations and are quarantined prior to launch with the goal of reducing the number of obligate pathogens carried to the ISS. Inflight, biocides are present in the potable water system and routine housekeeping measures are implemented. In the event that a microbiological anomaly should occur on the ISS, remediation activities are promptly initiated. There are various cleaning wipes aboard the ISS that are used for both housekeeping and remediation. Several criteria must be considered in the selection of the microbiologically active chemical(s) in the disinfectant wipes, as many chemicals that are potent microbial inhibitors also pose significant toxicological risks to crew health in the closed ISS environment. While the current methods of microbial control have been historically effective in mitigating infectious disease and biodeterioration risks for spaceflight missions, next generation sustainable antimicrobial technologies must be investigated as human spaceflight ventures extend in duration and move beyond low Earth orbit.