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This work describes the microbiological assessment and materials compatibility of a silver-based biocide as an alternative to iodine for the Crew Exploration Vehicle (CEV) and future spacecraft potable water systems. In addition to physical and operational anti-microbial counter-measures, the prevention of microbial growth, biofilm formation, and microbiologically induced corrosion in water distribution and storage systems requires maintenance of a biologically-effective, residual biocide concentration in solution and on the wetted surfaces of the system. Because of the potential for biocide depletion in water distribution systems and the development of acquired biocide resistance within microbial populations, even sterile water with residual biocide may, over time, support the growth and/or proliferation of bacteria that pose a risk to crew health and environmental systems.

The PESTO (Photosynthetic Experiment System Testing and Operation) experiment flew in the Biomass Production System (BPS) to International Space Station (ISS) on STS-110 (Atlantis) April 8, 2002, and returned on STS-111 (Endeavour) June 19, 2002, after 73 days in space. The ground control was conducted on a two-week delay at Kennedy Space Center in a BPS unit under environmental conditions comparable to ISS. Wheat (Triticum aestivum cv Apogee) and Brassica rapa cv Astroplant were independently grown in root modules for multiple grow-outs. On-orbit harvests, root modules exchanges and primings, seeds imbibitions, and gas and water samplings occurred at periodic intervals; all were replicated in ground controls. Many operations required crew handling and open access to individual chambers, allowing the exchange of microorganisms between the crew environment and the BPS modules.

The KSC Breadboard Scale Aerobic Bioreactor (B-SAB) was used to bioprocess inedible wheat crop residues to provide recycled nutrients to support crop growth in the JSC Variable Pressure Growth Chamber (VPGC) as part of the 91 day JSC-Lunar/Mars Life Support Test Project Phase III. To meet the wheat nutrient demand at JSC, the KSCB-SAB was operated at both a higher loading rate (35 gdw L-1 compared with 20 gdw L-1) and at a slower retention time (21 days compared with 8 days) than we had used in previous bioreactor (continuous stirred tank reactor - CSTR) studies. The bioreactor operated for 19 weeks-8 weeks startup and steady state stabilization then 11 weeks of operation with the broth harvested weekly. Filtered broth was amended with nutrients and transported to JSC for integration into the VPGC wheat growth component of L/MLSTP Phase III. Biodegradation of JSC wheat residues was a constant 45% during steady state bioreactor operation, and similar to previous B-SAB runs.

Spacecraft cabin air quality is influenced by a variety of factors. Beyond normal equipment offgassing and crew metabolic loads, the vehicle's operational configuration contributes significantly to overall air quality. Leaks from system equipment and payload facilities, operational status of the atmospheric scrubbing systems, and the introduction of new equipment and modules to the vehicle all influence air quality. The dynamics associated with changes in the International Space Station's (ISS ) configuration since the launch of the U.S. Segment's laboratory module, Destiny, is summarized. Key classes of trace chemical contaminants that are important to crew health and equipment performance are emphasized. The temporary effects associated with attaching each multi-purpose logistics module (MPLM) to the ISS and influence of in-flight air quality on the post-flight ground processing of the MPLM are explored.

With the installation of the Water Recovery System (WRS) during mission STS-126 in 2008, the International Space Station (ISS) added the capability to recover clean water for reuse from crewmember urine and atmospheric humidity condensate, including EVA (Extravehicular Activity) wastes. The ability to collect, store and process these waste streams is required to increase potable water recovery and support the ISS crew augmentation planned for 2009. During ground testing of the Urine Processing Assembly (UPA), one of two primary component subsystems that comprise the WRS, significant fouling was repeatedly observed in stored urine pretreated with 0.56% of chromium trioxide and sulfuric acid. During initial observation, presumptive microbiological growth clogged and damaged flight-rated hardware under test as part of a risk-mitigation Flight Experiment (FE).

Understanding the effects of dynamic thermal and vacuum regeneration on VOC desorption kinetics is needed for the development of regenerable trace contaminant control air revitalization systems. The effects of temperature and vacuum quality on the desorption kinetics of ethanol from Carbosieve SIII were examined using 1 hour regeneration cycles. The effect of vacuum quality on ethanol desorption was studied by exposing adsorption tubes loaded with ethanol to low pressures (1.0, 0.5, 0.3, and 0.12 atm) at various thermal regeneration temperatures (160, 100, 70, and 25 °C). At 1 atm of pressure, ethanol removal was found to increase from 2% at 25 °C, to 25% at 70 °C, to 55% at 100 °C, and to 77% at 160 °C. Decreasing the atmospheric pressure from 1 to 0.1 atm for 1 hr did not significantly enhance Carbosieve SIII regeneration at ambient temperatures (25 °C). However, heating the adsorbent at low pressures enhanced its regeneration.

A multitude of personal cleaning products, each of which typically contains multiple surfactants, are available for terrestrial use. Selection of surfactant(s) for use in extended space missions should consider, in addition to human comfort and cleansing power, potential impacts on biological processing systems under consideration for such missions. This paper reviews the surfactants present in commercial formulations, their proper nomenclature, and relevant properties such as foaming, biodegradability of organic fractions (both with respect to rate and pathway), presence of inorganic components (e.g., sulphate or counter ions such as sodium), and analytical methods for monitoring their concentrations in waste stream. The background information and results from preliminary testing are used to draw conclusions about the proper approach for selecting surfactants for use in space missions containing biological waste treatment systems.

A continuous leaching device was designed to extract inorganic nutrients from ALS solid wastes for recycling back to hydroponic plant growth systems. The system consists of a conveyor that carries the waste under a water spray. The leacher was used to extract nutrients from hydroponic rice crop residues. The highly aerated and nutrient-rich recirculation liquid supports microbial growth on all surfaces, which leads to biofouling that causes maintenance difficulties. However, it may be better than the standard leaching protocol, as it produces leachate with significantly reduced BOD. This would make it possible to use the leachate from this reactor in hydroponic plant systems without further processing.

Different options have been examined for providing minerals to plants for bioregeneration. The baseline option is to ship the minerals. The equivalent system mass of two different bioreactor systems for recycling a portion of these minerals, a fixed-film bioreactor and a stirred-tank reactor are calculated. Either option could reduce the ESM for providing these minerals for a 15-year mission to Mars, with 50% food closure.

This paper investigates error-contributing factors frequently encountered during plant starch content determinations by the widely used methodology based on the enzymatic/colorimetric determination of glucose released from enzymatic hydrolysis of starch. Due to the dynamics and variability of starch levels in plant tissues, inaccurate results were found to be associated with sampling and tissue preparation protocols. Other error-contributing factors included: (1) incomplete removal of interfering soluble sugars before starch hydrolysis, (2) non-specific hydrolysis during gelatinisation of starch granules, (3) incomplete hydrolysis of starch due to insufficient amounts of hydrolyzing enzyme, and (4) improper use of starch standards. A unified procedure that only requires 10-25 mg dry material is presented.

The purpose of this research is to determine the feasibility of a unique denitrifying composter to stabilize trash from space-habitation (STS, ISS, ALS) life support activities. Design criteria were derived from variables to be manipulated and those to be held constant. A pre-existing aerobic composter was used and engineering tests run to ensure that requirements were met. Key experimental variables were identified: NO3- concentration and rate of addition, O2 concentration, mixing duration and frequency, and inoculum. Independent variables were pH, temperature, moisture, C:N ratio, feed material, size reduction, feed addition rate, and mode of operation. Important performance parameters included: maximization of desired outcomes – BOD5 removal, CO2 production, waste stabilization, and denitrification – and minimization of undesired products – N2O, NH3, and volatile organic compounds.

This report describes the design, assembly, and testing of a modified, re-circulating drip flow reactor to quantify the electrical, optical, and thermal performance of solid-state ultraviolet (UV) lighting and semi-conducting photocatalyst for potable water disinfection by advanced oxidation processes. The reactor test assembly incorporates high-output UV-A Light Emitting Diodes (LEDs) with active thermal control to reject heat and generate reactive oxygen species from immobilized titanium dioxide attached to borosilicate glass in the laminar flow stream. Compared with UV-excimer and UV-mercury arc lamps, the UV-A LED system demonstrated excellent thermal stability and good electrical and optical performance.

The chemical specificity of several adsorbents, capable of being recycled by thermal desorption, was determined using volatile organic compounds (VOCs) found in ISS cabin air. These VOC adsorbents will be used to design a reusable filter to control ethylene in plant growth chambers and other STS/ISS biological payloads. A reusable filter to remove plant-produced ethylene from plant growth chambers could help minimize the mass and power use of plant flight hardware. Spaceflight-rated plant growth chambers employ either passive or active catalytic scrubbers for maintaining acceptable levels of VOCs. Passive systems require consumables, while active systems require power and their performance can be degraded in high humidity environments. Each adsorbent was loaded with known amounts of VOCs at a known flow rate. The filtering capacity and chemical specificity of each compound was determined from measurements pre- and post-filter VOC concentration.

Microorganisms will be an integral part of biologically based waste processing systems used for water purification or nutrient recycling on space flights. Establishment of these systems with a defined group of microorganisms will provide a standardized means for conferring specific properties to the system. The purpose of this study was to develop microbial inocula (a defined, constructed community and an undefined community) for initiation of plant-based graywater waste processing systems. To this end, small-subunit 16S rDNA sequence analysis was used to describe the population composition of microbial communities from a plant-based graywater waste treatment system and from an industrial wastewater treatment plant (WWTP). The clonal library of organisms from the graywater-degrading rhizosphere community suggested that members of the Cytophagales and Proteobacteria phylogenetic groups dominated. The clonal library of organisms from industrial WWTP was taxonomically more diverse.

Bioreactor technology for bioprocessing graywater solutions in microgravity is under development by NASA at Johnson Space Center and at major aerospace companies. Inoculum sources have been inconsistent. Startup and subsequent operation of ground-based bioreactors may have been adversely affected by this inconsistency and/or by inoculation procedures. The goal of the research reported in this paper is to develop an inoculum that will completely biodegrade Igepon T42 soap to carbon dioxide and water under anaerobic, denitrifying conditions and with process conditions set by bioreactor design requirements for microgravity operation. Potential inoculum sources from two habitats within the KSC-ALS breadboard project were developed for potential use. The effects of pH (7.2 vs. 9.0, buffered) on soap degradation by the two inocula was determined in a flask study. Nearly all of the soap was degraded at pH 7.2 while nearly none was degraded at pH 9.0. Both inocula behaved similarly.

The candidate crops that have been considered by NASA for providing moderate quantities of supplemental food for crew's consumption during near term or long duration missions include minimally processed “salad” species. Lettuce (cv. Flandria), radish (cv. Cherry Bomb II) and green onion (cv. Kinka) plants were grown under cool-white fluorescent (CWF) lamps with light intensities of 8.6, 17.2, or 25.8 mol m−2 d−1, at air temperatures of 25 and 28 °C, 50% relative humidity, and 1200 µmol mol−1 CO2. Following 35 days growth, final edible mass yields were recorded. All three species grown at 25 °C showed an increase in edible fresh mass and growth rates as light intensity increased. When grown at 28 °C however, the edible fresh mass and crop growth rate of radish, lettuce and onion was significantly reduced at all light intensities when compared to yields at 25 °C. Overall, results indicated that all three crops were sensitive to changes in light intensity and temperature.

Carbosieve SIII was used to filter dichloromethane (DCM) from a simulated spacecraft gas stream. This adsorbent was tested as a possible commercial-off-the-shelf (COTS) filtration solution to controlling spacecraft air quality. DCM is a halocarbon commonly used in manufacturing for cleaning and degreasing and is a typical component of equipment offgassing in spacecraft. The performance of the filter was measured in dry and humid atmospheres. A known concentration of DCM was passed through the adsorbent at a known flow rate. The adsorbent removed dichloromethane until it reached the breakthrough volume. Carbosieve SIII exposed to dry atmospheric conditions adsorbed more DCM than when exposed to humid air. Carbosieve SIII is a useful thermally regenerated adsorbent for filtering DCM from spacecraft cabin air. However, in humid environments the gas passes through the filter sooner due to co-adsorption of additional water vapor from the atmosphere.

This report describes ground testing of a commercial-off-the-shelf (COTS) water treatment device for contingency recovery of potable liquid from ersatz human urine to support spaceflight testing. The Forward Osmosis Bag (FOB) is a portable, passive water treatment device utilizing osmotic potential to move water across a layered, ultra-filtration membrane to remove pathogens and reject chemical contaminants. The FOB is capable of rejecting ≥90% of the salts, ≥85% of the Total Oxidizable Carbon (TOC), ≥95% of the Total Nitrogen (TN), and ≥93% of Urea-Nitrogen (BUN) in the ersatz urine while completely removing a mixed bacterial population of >108 cells per milliliter.

The development of a spaceflight-rated Porous Tube Insert Module (PTIM) nutrient delivery tray has facilitated a series of studies evaluating various aspects of water and nutrient delivery to plants as they would be cultivated in space. We report here on our first experiment using the PTIM with a software-driven feedback moisture sensor control strategy for maintaining root zone wetness level set-points. One-day-old wheat seedlings (Tritium aestivum cv Apogee; N=15) were inserted into each of three Substrate Compartments (SCs) pre-packed with 0.25–1 mm Profile™ substrate and maintained at root zone relative water content levels of 70, 80 and 90%. The SCs contained a bottom-situated porous tube around which a capillary mat was wrapped. Three Porous Tubes were planted using similar protocols (but without the substrate) and also maintained at these three moisture level set-points. Half-strength modified Hoagland’s nutrient solution was used to supply water and nutrients.

The objectives of these experiments were two fold: 1) to determine if accepted tissue fixation procedures can be adapted for long-term storage on-board the International Space Station (ISS) and 2) to test whether they are suitable for KSC Fixation Tubes (KFTs). Three tissue fixation parameters were tested: time, temperature and sample size.Fixation time:samples are normally fixed from several minutes to several hours, but because of the duration of the UF-1 mission to ISS, the tissue will be in fixative for up to 3 months. Super dwarf wheat tissue samples were fixed in either FAA (a fixative normally used for storage of plant tissues) or a glutaraldehyde-based fixative and stored for 100 days.