Space habitat

Abstract: Humans living and working in the harsh environment of space present many challenges for habitability engineers and microbiologists. Spacecraft must provide an internal environment in which physical (gas composition, pressure, temperature, and humidity), chemical, and biological environmental parameters are maintained at safe levels. Microorganisms are ubiquitous and will accompany all human-occupied spacecraft, but if biological contamination were to reach unacceptable levels, long-term human space flight would be impossible. Prevention of microbiological problems, therefore, must have a high priority. Historically, prevention of infectious disease in the crew has been the highest priority, but experience gained from the NASA-Mir program showed that microbial contamination of vehicle and life-support systems, such as biofouling of water and food, are of equal importance. The major sources of microbiological risk factors for astronauts include food, drinking water, air, surfaces, payloads, research animals, crew members, and personnel in close contact with the astronauts. In our efforts to eliminate or mitigate the negative effects of microorganisms in spacecraft, the National Aeronautics and Space Administration (NASA) implemented comprehensive microbial analyses of the major risk factors. This included the establishment of acceptability requirements for food, water, air, surfaces, and crew members. A robust monitoring program was then implemented to verify that the risks were within acceptable limits. Prevention of microbiological problems is preferred over mitigation of problems during flight, and preventive steps must begin very early in the design phase. Spacecraft development must include requirements to control free water from humidity, condensate, hygiene activities, and other releases. If water is available, microbes are likely to grow because sufficient nutrients are potentially available. Materials selected for the spacecraft must not promote or support microbial growth. Air filtration can dramatically reduce the number of airborne bacteria, fungi, and particulates in spacecraft breathing air. Waterborne bacteria can be reduced to acceptable levels by thermal inactivation of bacteria during water processing, along with a residual biocide, and filtration at the point of use can ensure safety. System design must include onboard capability to achieve recovery of the system from contamination. Robust housekeeping procedures that include periodic cleaning and disinfection will prevent high levels of microbial growth on surfaces. Food for consumption in space must be thoroughly tested for excessive microbial content and pathogens before launch. Thorough preflight examination of flight crews, consumables, payloads, and the environment can greatly reduce pathogens in spacecraft. Many of the lessons learned from the Space Shuttle and previous programs were applied in the early design phase of the International Space Station, resulting in the safest space habitat to date. This presentation describes the monitoring program for the International Space Station and will summarize results from preflight and on-orbit monitoring.

Abstract: The space habitat is a confined environment with a simple ecosystem that consists mainly of microorganisms and humans. Changes in the pathogenicity and virulence of bacteria, as well as in astronauts' immune systems, during spaceflight may pose potential hazards to crew health. To ensure microbiological safety in the space habitat, a comprehensive analysis of environmental microbiota is needed to understand the overall microbial world in this habitat. The resulting data contribute to evidence-based microbial monitoring, and continuous microbial monitoring will provide information regarding changes in bioburden and microbial ecosystem; this information is indispensable for microbiological management. Importantly, the majority of microbes in the environment are difficult to culture under conventional culture conditions. To improve understanding of the microbial community in the space habitat, culture-independent approaches are required. Furthermore, there is a need to assess the bioburden and physiological activity of microbes during future long-term space habitation, so that the "alert" and/or "action" level can be assessed based on real-time changes in the microbial ecosystem. Here, we review the microbial monitoring in the International Space Station-Kibo, and discuss how these results will be adapted to the microbial control in space habitation and pharmaceutical and food processing industries.