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Space flight and related factors such as stress appear to have an adverse effect on astronauts' immune systems. The presence of potentially pathogenic microbes including several genera of fungi reported from spacecraft environment may be a cause of concern in such situations. In order to study the role of such organisms in causing opportunistic or allergic diseases in crewmembers, we have tried to develop an animal model. BALB/c mice were suspended upside down for varying periods of time to induce stress, and their lymphocyte functions were evaluated. These studies indicate that the stress resulted in lowered mitogen induced lymphocyte stimulation as represented by 3H-thymidine uptake. We have also studied the ability of these animals to respond to Aspergillus fumigatus spores. The results of the study clearly demonstrate a definite down-regulation in T-cell proliferation and a higher incidence of infection with A. fumigatus.

Two simulated spacecraft water systems are being used to evaluate the effectiveness of iodine for controlling microbial contamination within such systems. An iodine concentration of about 2.0 mg/L is maintained in one system by passing ultrapure water through an iodinated ion exchange resin. Stainless steel coupons with electropolished and mechanically-polished sides are being used to monitor biofilm formation. Results after three years of operation show a single episode of significant bacterial growth in the iodinated system when the iodine level dropped to 1.9 mg/L. This growth was apparently controlled by replacing the iodinated ion exchange resin, thereby increasing the iodine level. The second batch of resin has remained effective in controlling microbial growth down to an iodine level of 1.0 mg/L. Scanning electron microscopy indicates that the iodine has impeded but may have not completely eliminated the formation of biofilm.

The ability of iodine to maintain microbial water quality in a simulated spacecraft water system is being studied. An iodine level of about 2.0 mg/L is maintained by passing ultrapure influent water through an iodinated ion exchange resin. Six liters are withdrawn daily and the chemical and microbial quality of the water is monitored regularly. Stainless steel coupons used to monitor biofilm formation are being analyzed by culture methods, epifluorescence microscopy, and scanning electron microscopy. Results from the first two years of operation show a single episode of high bacterial colony counts in the iodinated system. This growth was apparently controlled by replacing the iodinated ion exchange resin. Scanning electron microscopy indicates that the iodine has limited but not completely eliminated the formation of biofilm during the first two years of operation.

The investigation and development of a chemiluminescence based ethanol detection concept into a biosensor system is described. The biosensor uses alcohol oxidase to catalyze the reaction of short chain primary alcohols with elemental oxygen to produce hydrogen peroxide and the corresponding aldehyde. The reaction of hydrogen peroxide with an organic luminophore in the presence of a sufficient electric field results in emission of blue light with peak intensity at 425nm. The chemiluminescent light intensity is directly proportional to the alcohol concentration of the sample. The aqueous phase chemistry required for sensor operation is implemented using solid phase modules which adjust the pH of the influent stream, catalyze the oxidation of alcohol, provide the controlled addition of the luminophore to the flowing aqueous stream, and minimize the requirement for expendables. Precise control of the pH has proven essential for the long-term sustained release of the luminophore.

An aqueous phase catalytic oxidation system (APCOS) was designed, tested and delivered to NASA/Johnson Space Center (JSC). The APCOS removes residual organic impurities in reclaimed water to a level acceptable for potable use and to provide disinfection. The reactor, which contains a heterogeneous catalyst consisting of a noble metal on an inert support medium, operates at 120 - 150 °C and at fluid pressures of several atmospheres to maintain an aqueous liquid phase. Pressurized gaseous oxygen, used as the oxidant, is directly injected into the liquid phase. A description of the subsystems process hardware is presented. The APCOS was demonstrated to mineralize organic impurities at concentrations of 100 mg/L total organic carbon (TOC) to < .5 mg/L (<500 μg/L TOC). In addition, disinfection features were demonstrated with microbial challenge tests.

In 1985, the Man-Systems Division at the Johnson Space Center initiated a program for the development of a whole body shower suitable for operation in a microgravity environment. Supporting this development effort has been a systematic research program focused on four critical aspects of the design (i.e., human factors engineering, biomedical, mechanical, and electrical) and on the interfaces between the whole body shower system and the other systems to be aboard the Space Station (e.g., the water reclamation and air revitalization systems). A series of tests has been conducted to help define the design requirements for the whole body shower. Crew interface research has identified major design parameters related to enclosure configurations, consumable quantities, operation timelines, displays and controls, and shower and cleanup protocols.

A breadboard Electrochemical Water Recovery System (EWRS) that is designed to produce potable water from a composite waste stream without the use of expendables is described in this paper. Umpqua Research Company working together with NASA/JSC developed a sequential three-step process to accomplish this task. Electrolysis removes approximately 60% of the organic contaminants from ersatz composite waste water containing a total organic carbon (TOC) concentration of 707 mg/L. The contaminants in this solution consist of organic and inorganic impurities common to laundry, shower, handwash, and urine waste water. Useful gases and organic acids are the chief by-products of the first step. The partially oxidized electrolysis solution is then transferred to the electrodialysis process where ionized organic and inorganic species are concentrated into a brine. The deionized solution of recovered water contains ∼6% of the original organic contaminants and >90% of the original water.

In-flight contamination control has been an important concern of NASA since the first manned missions. Previous experience has shown that uncontrolled growth of bacteria and fungi can have a detrimental effect on both the health of the crew and the proper operation of flight hardware. It is therefore imperative to develop a safe, effective method of microbial control. Spacecraft application dictates a more stringent set of requirements for biocide selection than is usually necessary for terrestrial situations. Toxicity of the biocide is the driving factor for disinfectant choice in spacecraft. This concern greatly reduces the number and types of chemical agents that can be used as disinfectants. Currently, four biocide candidates (hydrogen peroxide, quaternary ammonium compounds, iodine, glutaraldehyde) are being evaluated as potential surface disinfectants for Space Station Freedom.

The work presented in this paper summarizes the early results of an integrated advanced water recovery system test conducted by the Crew and Thermal Systems Division (CTSD) at NASA-Johnson Space Center (JSC). The system design and the results of the first two months of operation are presented. The overall objective of this test is to demonstrate the capability of an integrated advanced water recovery system to produce potable quality water for at least six months. Each subsystem is designed for operation in microgravity. The primary treatment system consists of a biological system for organic carbon and ammonia removal. Dissolved solids are removed by reverse osmosis and air evaporation systems. Finally, ion exchange technology in combination with photolysis or photocatalysis is used for polishing of the effluent water stream. The wastewater stream consists of urine and urine flush water, hygiene wastewater and a simulated humidity condensate.

Electrooxidation is a means of removing organic solutes directly from waste waters without the use of chemical expendables. Research sponsored by NASA Johnson Space Center is currently being pursued at Texas A&M University to demonstrate the feasibility of the concept for oxidation of organic impurities common to urine, shower waters and space habitat humidity condensates. Electrooxidation of urine and waste water ersatz was experimentally demonstrated. This paper discusses the electrooxidation principle, reaction kinetics, efficiency, power, size, experimental test results and water reclamation applications. Process operating potentials and the use of anodic oxidation potentials that are sufficiently low to avoid oxygen formation and chloride oxidation are described. The design of a novel electrochemical system that incorporates a membrane-based electrolyte based on parametric test data and current fuel cell technology is presented.

This paper addresses the derivation of chemical ersatz recipes for use in the evaluation of development hardware designed for advanced spacecraft water recovery systems. The recipes simulate characteristics of wastewater generated on a transit mission and on an early planetary base (EPB). In addition, recipes are provided which simulate the water quality of the early planetary base wastewater as it moves through a combination biological and physical-chemical water recovery system. These ersatz are considered to be accurate representations of the wastewater as it passes through primary, secondary, and tertiary processing stages. The EPB ersatz formulas are based on chemical analyses of an integrated water recovery system performance test that was conducted over a period of one year. The major inorganic and organic chemical impurities in the raw wastewater, and in the effluent from the various subsystems, were identified and quantified.

We evaluated the ability of a 3% (8800 μM) solution of hydrogen peroxide to kill 12 strains of bacteria and 12 strains of fungi. A 1:4 dilution of 3% H2O2, equivalent to 1100 μM, was lethal to all the tested strains. If the situation calls for a nonaggressive disinfectant without residue or toxic aftereffects, 3% H2O2 seems an ideal choice.

Controlling microbial growth and biofilm formation in spacecraft water-distribution systems is necessary to protect the health of the crew. Methods to decontaminate the water system in flight may be needed to support long-term missions. We evaluated the ability of iodine and ozone to kill attached bacteria and remove biofilms formed on stainless steel coupons. The biofilms were developed by placing the coupons in a manifold attached to the effluent line of a simulated spacecraft water-distribution system. After biofilms were established, the coupons were removed and placed in a treatment manifold in a separate water treatment system where they were exposed to the chemical treatments for various periods. Disinfection efficiency over time was measured by counting the bacteria that could be recovered from the coupons using a sonication and plate count technique. Scanning electron microscopy was also used to determine whether the treatments actually removed the biofilm.

The active control of problematic microbial populations aboard spacecraft, and within future lunar and planetary habitats is a fundamental Advanced Life Support (ALS) requirement to ensure the long-term protection of crewmembers from infectious disease, and to shield materials and equipment from biofouling and biodegradation. The development of effective antimicrobial coatings and materials is an important first step towards achieving this goal and was the focus of our research. A variety of materials were coated with antibacterial and antifungal agents using covalent linkages. Substrates included both granular media and materials of construction. Granular media may be employed to reduce the number of viable microorganisms within flowing aqueous streams, to inhibit the colonization and formation of biofilms within piping, tubing and instrumentation, and to amplify the biocidal activity of low aqueous iodine concentrations.

This paper provides an assessment of functional characteristics needed in the microbial water analysis system being developed for Space Station. Available technology is reviewed with respect to performing microbial monitoring, isolation, or identification functions. An integrated system composed of three different technologies is presented.

The work presented in this paper summarizes the performance of subsystems used during an integrated advanced water recovery system test conducted by the Crew and Thermal Systems Division (CTSD) at NASA-Johnson Space Center (JSC). The overall objective of this test was to demonstrate the capability of an integrated advanced water recovery system to produce potable quality water for at least six months. Each subsystem was designed for operation in microgravity. The primary treatment system consisted of a biological system for organic carbon and ammonia removal. Dissolved solids were removed by reverse osmosis and air evaporation systems. Finally, ion exchange technology in combination with photolysis or photocatalysis was used for polishing of the effluent water stream. The wastewater stream consisted of urine and urine flush water, hygiene wastewater and a simulated humidity condensate.

Weightlessness, cosmic radiation and other space flight related conditions may adversely impact the physiology and immune status of the crew. Since microorganisms will surely be present in space habitats, the effects of space on microbial metabolic and physiologic functions will depend upon environmental conditions, types of organisms, and the duration of the flight. Because humans will conduct long-duration space missions, space microbiology must address the effect of alterations in microbial function during space flight. Even innocuous microorganisms and endogenous flora may become etiologic agents for disease during long missions. The microbial population in the closed environments of spacecraft may also become a source of toxic metabolites or the biodegradation of materials. This paper reviews studies concerning microbial behavior in closed environments, simulated microgravity, and actual space flight.

To mitigate risk to crew health, the microbial surveillance of the quality of potable water sources of the International Space Station (ISS) has been ongoing since before the arrival of the first permanent crew. These water sources have included stored ground-supplied water, water produced by the Shuttle fuel cells during flight, and ISS humidity condensate that is reclaimed and processed. In-flight monitoring was accomplished using a self-contained filtering system designed to allow bacterial growth and enumeration during flight. Upon return to Earth, microbial isolates were identified using 16S ribosomal gene sequencing. While the predominant isolates were common Gram negative bacteria including Ralstonia eutropha, Methylobacterium fujisawaense, and Sphingomonas paucimobilis, opportunistic pathogens such as Stenotrophomonas maltophilia and Pseudomonas aeruginosa were also isolated.

One of the proposed methods for monitoring the microbial quality of the water supply aboard the International Space Station is membrane filtration. We adapted this method for space flight by using an off-the-shelf filter unit developed by Millipore. This sealed unit allows liquid to be filtered through a 0.45 μm cellulose acetate filter that sits atop an absorbent pad to which growth medium is added. We combined a tetrazolium dye with R2A medium to allow microbial colonies to be seen easily, and modified the medium to remain stable over 70 weeks at 25°C. This hardware was assembled and tested in the laboratory and during parabolic flight; a modified version was then flown on STS-66. After the STS-66 mission, a back-up plastic syringe and an all-metal syringe pump were added to the kit, and the hardware was used successfully to evaluate water quality aboard the Russian Mir space station.

With the restructure and funding changes for Space Station Freedom, the Environmental Health System (EHS)/Microbiology Subsystem revised its scheduling and operational requirements for component hardware. The function of the Microbiology Subsystem is to monitor the environmental quality of air, water, and internal surfaces and, in part, crew health on board Space Station. Its critical role shall be the identification of microbial contaminants in the environment that may cause system degradation, produce unsanitary or pathogenic conditions, or reduce crew and mission effectiveness. EHS/Microbiology operations and equipment shall be introduced in concert with a phased assembly sequence, from Man Tended Capability (MTC) through Permanently Manned Capability (PMC). Effective Microbiology operations and subsystem components will assure a safe, habitable, and useful spacecraft environment for life sciences research and long-term manned exploration.