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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.

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.

The effects of acoustic levels in manned space vehicles was not thoroughly appreciated until the STS 40 mission, Spacelab Life Sciences 1 (June, 1991). Previous to that mission, waivers were submitted and equipment operated without overwhelming effect on ongoing flight activities. The factors of multiple pieces of noise producing equipment operating simultaneously, operating in the vicinity of crew sleep stations, and operating for this long of a mission (10 days) became relevant in crew tolerance, fatigue, communication, and permanent shifts in hearing thresholds. Because this was a life sciences mission, accurate instrument measurements were obtained of acoustic levels in the middeck, flight deck and spacelab during flight and physiological measurements were obtained from the crew members during all phases of the mission. Due to the STS 40 results, a Spacelab/Payloads Acoustics Working Group (SPAWG) was formed post flight to address acceptable acoustic limits.

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 white rat, Rattus norvegicus has been used extensively in microgravity flights. Initial NASA flight experiments with rats supported the Shuttle Student Involvement Program (SSIP). Hardware to house the rats was called the Animal Enclosure Module (AEM). The AEM for the SSIP, fit into a middeck locker. Potatoes provided water; food bars, glued on the walls, provided nourishment. Waste was absorbed and odor and microbial growth controlled by sandwiched phosphoric acid treated charcoal and filter materials utilizing much of the technology employed in the Rodent Research Animal Holding Facility, a Spacelab piece of equipment. The SSIP AEM potato “watering” system succumbed to mold and had to be replaced by real water contained within plasma bags. A metal enclosure housed the plasma bags between two heavy springs which forced water through animal activated lixits.