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Management of human feces and wastes is a major challenge in space vehicles due to the potential biohazards and malodorous compounds emanating during collection and storage of feces and wastes. To facilitate safe, yet realistic human waste management research, we have previously developed human fecal simulants for research activities. The odoriferous compounds in feces and wastes reduce the quality of life for astronauts, can reduce performance, and can even cause health problems. The major odoriferous compounds of concern belong to four groups of chemicals, volatile fatty acids, volatile sulfurous compounds, nitrogenous compounds and phenols. This paper attempts to review the problem of odor detection and odor control with advanced technology. There has been considerable progress in odor detection and control in the animal industry and in the dental profession.

The inedible portion of plant biomass in closed regenerative life support systems must be reprocessed producing recyclable by-products such as carbon dioxide, sugars, and other useful organic species. High solids biomass slurries containing up to 27 wt% were successfully prepared in a stirred batch reactor and then pumped using a single piston valveless pump. Wheat straw, potato, and tomato crop residues were acid hydrolyzed using 1.2 wt% sulfuric acid at 180°C and 1.2 MPa for 0.75-1.5 hours. Viscosity for a 25 wt% acid hydrolyzed wheat straw emulsion (Bingham-plastic) was 6.5 centipoise at 3 cm/sec and 25°C.

Waste Management Systems (WMSs) designed for use aboard long-term spacecraft missions and within Lunar and planetary habitations must reduce volume and recover useful resources from solid wastes, as well as impart chemical and microbial stability to stored wastes. Many WMS processes produce high concentrations of toxic emissions that can periodically overwhelm Trace Contaminant Control Systems (TCCSs) designed to handle nominal atmospheric contaminants. A prototype Catalytic Oxidation System (COS) has been developed for this contingency, and when mated to different WMS processes, will treat these toxic emissions on an as-needed basis. The COS reactor utilizes a platinum and ruthenium bimetallic catalyst supported on mesoporous zirconia that is highly active and oxidizes at relatively low temperature a wide variety of volatile organic compounds (VOCs) and inorganic toxic emissions produced by WMS processes.

Several solid waste management (SWM) systems currently under development for spacecraft deployment result in the production of a variety of toxic gaseous contaminants. Examples include the Plastic Melt Waste Compactor (PMWC) at NASA - Ames Research Center1, the Oxidation/Pyrolysis system at Advanced Fuel Research2, and the Microwave Powered Solid Waste Stabilization and Water Recovery (MWSWS&WR) System at UMPQUA Research Company (URC). The current International Space Station (ISS) airborne contaminant removal system, the Trace Contaminant Control Subassembly (TCCS), is designed to efficiently process nominal airborne contaminants in spacecraft cabin air. However, the TCCS has no capability to periodically process the highly concentrated toxic vapors of variable composition, which are generated during solid waste processing, without significant modifications.

Handling and processing human feces in space habitats is a major concern and needs to be addressed for the Crew Exploration Vehicle (CEV) as well as for future exploration activities. In order to ensure crew health and safety, feces should either be isolated in a dried form to prevent microbial activity, or be processed to yield a non-biohazardous product using a reliable technology. During laboratory testing of new feces processing technologies, use of “real” feces can impede progress due to practical issues such as safety and handling thereby limiting experimental investigations. The availability of a non-hazardous simulant or analogue of feces can overcome this limitation. Use of a simulant can speed up research and ensure a safe laboratory environment. At Ames Research Center, we have undertaken the task of developing human fecal simulants. In field investigations, human feces show wide variations in their chemical/physical composition.

Spacelab-J was an international Spacelab mission with numerous innovative Japanese and American materials and life science experiments. Two of the Spacelab-J experiments were designed over a period of more than a decade by a team from NASA-Ames Research Center. The Frog Embryology Experiment investigated and is helping to resolve a century-long quandary on the effects of gravity on amphibian development. The Autogenic Feedback Training Experiment, flown on Spacelab-J as part of a multi-mission investigation, studied the effects of Autogenic Feedback Therapy on limiting the effects of Space Motion Sickness on astronauts. Both experiments employed the use of a wide variety of specially designed hardware to achieve the experiment objectives.

Space Station Freedom will provide an opportunity to conduct long duration life sciences research on plants and animals in a microgravity environment. Studies will be able to determine the rate of change of various processes in animals, e.g., calcium loss from bones, muscle atrophy, etc., determine the effect of microgravity on plant respiration and transpiration, and assess the impact of the microgravity environment over multiple generations for both plants and animals. However, all of these processes may also be affected by the 5.3 mm Hg partial pressure of CO2 (7000 ppm) currently specified for Space Station Freedom. The specifications for the plant and animal habitats to be developed as part of the Centrifuge Facility require that the CO2 level for plants be controlled over the range of 0.23 -2.3 mm Hg (300 to 3000 ppm ± 10-50 ppm) and that the atmospheric composition (CO2 level) for rodents be ± 1 % of the cabin composition.

The demanding performance requirements of advanced turbine-powered tactical aircraft have made it important to understand and accurately evaluate the propulsion system/airframe interactions. The turbine engine multi-mission propulsion simulator offers the potential for accurate evaluation of these interactions by permitting the simultaneous simulation of inlet/airframe/nozzle flowfields on a single wind tunnel model. Extensive simulator usage is expected during developmental testing of supersonic V/STOL and in-flight thrust vectoring configurations, which have significant flowfield interactions. The simulator has been successfully demonstrated in a wind tunnel test program, and is currently undergoing development to a more compact version.

Nitrogen use efficiency in hydroponic plant growth chambers is reduced by microbial denitrification. A computer-controlled bioreactor system was developed to investigate methods for controlling denitrification in hydroponic plant growth chambers envisioned for use on long duration space missions. Through regulation of O2 and NO3- levels in the bioreactor, the rate of denitrification of pure cultures was controlled. This control strategy may be used to favor plant nitrate uptake in the presence of denitrifying bacteria in hydroponic systems. Reducing denitrification provides advantages to advanced life support (ALS) systems by improving crop nitrogen use efficiency, reducing fixed-nitrogen demand, and reducing gaseous wastes (N2O and N2).