There are several well-documented health risks associated with prolonged exposure to microgravity, including muscle atrophy, bone density loss, and alterations in organ function and overall health. Astronauts frequently report symptoms indicative of immune dysfunction, such as skin rashes and other inflammatory conditions. Recent research led by Rodolfo A. Salido and Haoqi Nina Zhao from the University of California San Diego (UCSD) suggests that these health issues might be exacerbated by the hyper-sterile environment inside spacecraft, especially the International Space Station (ISS). Their findings indicate that increasing the number of microbes within the ISS could potentially improve astronaut health.
Research Methodology
This study represents a collaborative effort involving astronauts stationed aboard the ISS, who collected samples from 803 different surfaces—an unprecedented number. By conducting extensive microbial profiling, the researchers aimed to characterize the microbial diversity present within the ISS environment. A comparison was made between the ISS and various human-built environments on Earth.
During the study, the scientists cataloged bacteria and associated chemical signatures found in each sample and developed three-dimensional maps to visualize where each type is located and how they interact with each other. The researchers observed that microbial diversity aboard the ISS is markedly lower than that found in most terrestrial settings, excluding certain urban and industrialized environments like hospitals.
Findings
The analysis undertaken by the research teams revealed that chemical residues from cleaning products and disinfectants were prevalent throughout the ISS. Moreover, astronauts introduced most microbes within the station in the form of shed skin cells. Interestingly, distinct microbial communities were identified in different modules of the ISS, with varied chemical signatures corresponding to the purpose of each module. For instance, modules used for dining and food preparation revealed a wider array of food-related microbes, while the station's toilet had greater concentrations of microbes associated with urine and fecal matter.
“We observed that the amount of disinfectant on ISS surfaces is highly correlated with a decline in microbial diversity in various areas of the station,” stated Zhao in a Cell Press release. These findings underscore that increasing Earth-derived microbes on the ISS could foster healthier environments for astronauts. Salido noted:
“Future built environments, including space stations, could benefit from intentionally fostering diverse microbial communities that better mimic the natural microbial exposures experienced on Earth, rather than depending on starkly sanitized conditions. If we aspire for life to flourish beyond Earth, we cannot merely send a small fraction of Earth’s life forms into space and anticipate success. We must consider what additional beneficial species we should be providing to help astronauts develop sustainable ecosystems.”
Comparative Microbial Diversity
The examination concluded that the microbial communities aboard the ISS exhibit significantly lower diversity compared to most Earth settings, with the exception of specific urban and healthcare environments. Additionally, the study illustrated that typical environmental microbes usually found in soil and water were virtually absent on ISS surfaces. The authors draw parallels to research indicating how gardening promotes a healthy immune system—it would seem that incorporating desirable microbes and their substrates into the ISS could enhance astronaut health without compromising hygiene.
Future Directions
Co-author Robin Knight, a computational microbiologist at UCSD and leader of the Knight Lab, emphasized, “The contrast between healthy soil exposure from gardening and having no microbial influx in an enclosed environment, which can lead to unhealthy residues, is stark.”
The ongoing research aims to refine methods for identifying potentially harmful microbes and understanding how certain environmental metabolites could serve as indicators for astronaut health. The techniques and knowledge garnered from this investigation could also prove beneficial in enhancing the well-being of individuals residing in sterile conditions on Earth.
This study has been supported by several institutions, including the National Institute of Health (NIH), the Alfred P. Sloan Foundation, UCSD, the Center for the Advancement of Science in Space (CASIS), and the ISS National Laboratory. The details of their findings are encapsulated in the article, “The International Space Station has a unique and extreme microbial and chemical environment driven by use patterns,” which was published in the journal Cell on February 27.
Conclusion
The implications of these findings extend beyond the realm of astronaut health; they challenge existing paradigms around environmental sterility in human habitats, especially those associated with healthcare and space exploration. Recognizing the importance of microbial ecosystems may redefine strategies for maintaining health in space and other isolated human environments.
Literature and References
- The International Space Station has a unique and extreme microbial and chemical environment driven by use patterns. Cell.
- Chiba University-UC San Diego Center for Mucosal Immunology Allergy and Vaccines.
- National Institute of Health (NIH).
- Alfred P. Sloan Foundation.
- ISS National Laboratory.
For further information, see the following studies:
