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Bioregenerative resource recovery components for Advanced Life Support systems will need to be reliable and stable for long duration space travel. Since 1989, bioregenerative life support research at the ALS Breadboard Project has examined processing of inedible crop residues in bioreactors for recovery of nutrients for replenishment of crop hydroponic solutions. Bioreactor operation has been reliable as demonstrated by continuous operation for up to 418 days with long periods of steady state conditions. Bioreactors have demonstrated stability following unplanned, non-lethal perturbations in pH, temperature, dissolved oxygen, and inedible residue supply. In each instance, a rapid return to steady state conditions was observed.

The National Aeronautics and Space Administration (NASA) intends to continue the human exploration of outer space. Long duration missions will require the development of reliable regenerative life support processes. The intent of this paper is to define the Kennedy Space Center Controlled Ecological Life Support System (CELSS) research plan for the development and testing of three candidate biological processors for a hybrid biological and physical-chemical waste recycling system. The system would be capable of reclaiming from inedible plant biomass, human metabolic waste, and gray water those components needed for plant growth (carbon dioxide, water, and inorganic salts), while eliminating noxious compounds and maximizing system closure. We will colaborate with AMES Research Center (ARC), Johnson Space Center (JSC), and academia, to design a functional biological-based waste processing system that could be integrated with the planned Human Rated Test Facility (HRTF) at JSC.

Because of mass and power constraints in spacecraft, plant growth units designed for spaceflight have limited volume and low photosynthetic photon flux (PPF). Sufficient lighting and nutrient delivery are basic challenges to the success of supporting long-term plant growth in space. At the Kennedy Space Center, plant lighting and nutrient delivery hardware currently under NASA-sponsored development are being evaluated to define some of the fundamental issues associated with producing different fresh salad crops. Lettuce crops performed well under all nutrient delivery systems and lighting sources tested. Spinach and radish yields were lower in the presence of zeoponic media (using an ASTROCULTURE™ root tray) relative to plant grown in conventional NFT systems. Within each nutrient delivery system, yields of salad crops under red LEDs + blue light were similar to those crops grown under conventional white light.

The effects of volume-reduction via compaction (VR-C) on microbial loads and microbially-produced noxious odors during post-treatment storage were investigated. The Crew Exploration Vehicle (CEV) / Orion simulated food trash compartment wastes (FTCW) consisted of 80% food trash with packaging and 20% wipes. Compaction was compared with a non-compacted control and will provide a baseline for comparison with other treatment technologies. The first study was a timecourse with post-treatment storage durations of 1, 2, 4, and 6 weeks. Key response variables were: O2 consumption and CO2 production from waste biodegradation and microbiological assays consisting of total counts and culturable counts of (a) aerobic and anaerobic bacteria, (b) aerobic and anaerobic spore-forming bacteria, (c) specific bacteria including Pseudomonas aeruginosa, Burkholderia cepacia, and Staphylococcus aureus counts, and (d) molds at run termination.

The PESTO (Photosynthesis Experiment and System Testing and Operation) spaceflight experiment is designed to directly measure gas exchange of developing stands of wheat (Triticum aestivum L.) on the International Space Station (ISS). Gas exchange measurements will characterize photosynthesis and transpiration in microgravity at different stages of development. The Biomass Production System (BPS), a double middeck-sized plant growth will be the plant growth hardware used to support this experiment on-board ISS. This report presents results from a 10-day functional test of PESTO protocols in the BPS. Wheat canopy CO2 assimilation rate for 14-24 day-old plants grown in the BPS chambers was 6-7 μmol m-2 s-1 during this test. Plant responses to CO2 and photosynthetic photon flux (PPF) response curves were obtained at different stages of development by altering CO2 and light conditions.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.