Characterization of Spacesuit Associated Microbial Communities and Their Implications for NASA Missions

Abstract

BackgroundCrewed National Aeronautics and Space Administration (NASA) missions to other solar system bodies are currently being planned. One high-profile scientific focus during such expeditions would be life detection, specifically the discovery of past or present microbial life, if they exist. However, both humans and associated objects typically carry a high microbial burden. Thus, it is essential to distinguish between microbes brought with the expedition and those present on the exploring planets. Modern spacesuits are unique, customized spacecraft which provide protection, mobility and life support to crew during spacewalks, yet they vent, and the mobility of microbes through spacesuits has not been studied.ResultsTo evaluate the microbial colonization of spacesuits, NASA used an Extravehicular Activity swab kit to examine viable microbial populations of 48 samples from spacesuits using both traditional microbiological methods and molecular sequencing methods. The cultivable microbial population ranged from below the detection limit to 9 × 102 colony forming units per 25 cm2 of sample and also significantly varied by the location. The cultivable microbial diversity was dominated by members of Bacillus, Arthrobacter, and Ascomycota. However, 16S rRNA-based viable bacterial burden ranged from 105 to 106 copies per 25 cm2 of sample. Shotgun metagenome sequencing revealed the presence of a diverse microbial population on the spacesuit surfaces, including Curtobacterium and Methylobacterium from across all sets of spacesuits in high abundance. Among bacterial species identified, higher abundance of Cutibacterium acnes, Methylobacterium oryzae, and M. phyllosphaerae reads were documented.ConclusionThe results of this study provide evidence that identical microbial strains may live on the wrist joint, inner gauntlet, and outer gauntlet of spacesuits. This raises the possibility, but does not confirm that microbial contaminants on the outside of the suits could contaminate planetary science operations unless additional measures are taken. Overall, these data provide the first estimate of microbial distribution associated with spacesuit surfaces, which will help future mission planners develop effective planetary protection strategies.

In Situ Optimized Substrate Witness Plates: Ground Truth for Key Processes on the Moon and Other Planets

“…given that humans and associated exploration objects may carry a high microbial burden (Danko et al, 2021). Currently, space suits leak continuously during use without any sort of filtration.…”

“…These tracking methods may be especially important given venting and leakage from the types of space suits that may be used on the Moon and other bodies (Campbell, 2011; Papale et al., 2013; Paul et al., 2010), particularly given that humans and associated exploration objects may carry a high microbial burden (Danko et al., 2021). Currently, space suits leak continuously during use without any sort of filtration.…”

The crewed journey to Mars and its implications for the human microbiome

“…These microorganisms may also live and survive on spacesuits used for spacecraft maintenance. In simulations on Earth, microorganisms were identified on space suits [ 60 ]. Future studies need to establish possible contamination routes from inside the spacecraft via space suits onto the exterior of the spacecraft, especially in terms of planetary protection of Mars.…”

An airlock concept to reduce contamination risks during the human exploration of Mars

“…First, because none were designed to avoid microbial contamination: that was not a requirement for the systems they have been part of. When an astronaut comes out of the ISS Quest Joint Airlock (today’s state-of-the-art airlock), for instance, about a pound of non-sterile air is vented out when opening the hatch, and astronauts carry large numbers of microorganisms on the outside of their suits 13 . Second, because no measures have been taken to minimize backward biological contamination.…”