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Over the last three years, the University of Utah (UofU), NASA Ames Research Center (ARC), and Reaction Engineering International (REI) have been developing an incineration system for the regeneration of components in waste materials for long-term life support systems. The system includes a fluidized bed combustor and a catalytic flue gas clean up system. An experimental version of the incinerator was built at the UofU. The incinerator was tested and modified at ARC and then operated during the Phase III human testing at NASA Johnson Space Center (JSC) during 1997. This paper presents the results of the work at the three locations: the design and testing at UofU, the testing and modification at ARC, and the integration and operation during the Phase III tests at JSC.

Lunar and martian materials can be processed and used at planetary outposts to reduce the need (and thus the cost) of transporting supplies from Earth. A variety of uses for indigenous, on-site materials have been suggested, including uses as rocket propellants, construction materials, and life support materials. Utilization of on-site resources will supplement Regenerative Life Support Systems (RLSS) that will be needed to regenerate air, water, and wastes, and to produce food (e.g., plants) for human consumption during long-duration space missions.

In “Theory and Application of the Equivalent System Mass Metric,” Levri, Vaccari, and Drysdale computed the Equivalent System Mass (ESM) of crew time. ESM is a cost-type metric based on allocated mass that is often used in life support systems. The previous paper suggested that the cost per hour of crew time should be equal to the ESM of the life support system, divided by the number of available crew work hours. We suggest here that the mass cost for additional crew time may be as large as the total mission mass or as small as the added mass of consumables, depending on how much more crew time is needed. If the increased mission work load requires flying additional crewmembers, the total mass and cost of the mission increases roughly proportionally to crew size. But if the needed work can be done merely by extending the mission duration, the required additional mass is only that of the food and supplies to be consumed during the time extension.

As part of its integrated system test bed capability, NASA's Advanced Life Support Program has undertaken the development of a large-scale advanced life support facility capable of supporting long-duration testing of integrated, regenerative biological and physicochemical life support systems. This facility--the Advanced Life Support Human-Rated Test Facility (HRTF) is currently being built at the Johnson Space Center. The HRTF is comprised of a series of interconnected chambers with a sealed internal environment capable of supporting a test crew of four for periods exceeding one year. The life support system will consist of both biological and physicochemical components and will perform air revitalization, water recovery, food production, solid waste processing, thermal management, and integrated command and control functions. Currently, a portion of this multichamber facility has been constructed and is being outfitted with basic utilities and infrastructure.

Long duration missions pose substantial new challenges for solid waste management in Advanced Life Support (ALS) systems. These possibly include storing large volumes of waste material in a safe manner, rendering wastes stable or sterilized for extended periods of time, and/or processing wastes for recovery of vital resources. This is further complicated because future missions remain ill-defined with respect to waste stream quantity, composition and generation schedule. Without definitive knowledge of this information, development of mission requirements is hampered. Additionally, even if waste streams were well characterized, other operational and processing needs require clarification (e.g. resource recovery requirements and planetary protection constraints). Therefore, the development of solid waste management (SWM) subsystem requirements for long duration space missions is an inherently uncertain, complex and iterative process.

NASA's Advanced Life Support Program has included as part of its long-range planning the development of a large-scale advanced life support facility capable of supporting long-duration testing of integrated, regenerative biological and physicochemical life support systems. As the designated NASA Field Center responsible for integration and testing of advanced life support systems, Johnson Space Center has undertaken the development of such a facility--the Advanced Life Support Human-Rated Test Facility (HRTF). As conceived, the HRTF is an interconnected five-chamber facility with a sealed internal environment capable of supporting a test crew of four for periods exceeding one year. The life support system which sustains the crew consists of both biological and physicochemical components and will perform air revitalization, water recovery, food production, solid waste processing, thermal management, and integrated control and monitoring functions.

Advanced space life support systems, especially systems that include growing plants to produce food, require the recovery of resources - primarily carbon dioxide and water - from various hydrocarbon wastes. Supercritical water oxidation (SCWO) of wastes is one of several possible techniques for oxidizing waste organics to recover the carbon dioxide and water. Supercritical water oxidation has the advantages of fast kinetics, complete oxidation, and the minimization of undesirable side products. However, the SCWO process requires further development before the process can be implemented in space life systems. One of the SCWO development needs is in the area of destruction of insoluble solids - such as inedible biomass or human wastes. Insoluble solids have to be introduced into a SCWO reactor as particles, and it can be expected that the particle size of the solids will affect the rate of reaction.

A variety of techniques, including supercritical water oxidation, fluidized bed combustion, and microwave incineration have been applied to the destruction of solid wastes produced in regenerative life support systems supporting long duration manned missions. Among potential problems which still deserve attention are the need for operation in a variety of gravitational environments, and the requirement for improved methods of presenting concentrated solids to the reactor. Significant improvements in these areas are made possible through employment of the magnetically assisted gasification process. In this paper, magnetic methods are described for manipulating the degree of consolidation or fluidization of granular ferromagnetic media, for application in a gravity independent three step solid waste destruction process.

Of the many competing technologies for resource recovery from solid wastes for long duration manned missions such as a lunar or Mars base, incineration technology is one of the most promising and certainly the most well developed in a terrestrial sense. An incinerator was used to recover and recycle part of the waste produced during the Early Human Testing Initiative Phase 3 (EHTI 3) at Johnson Space Center. The fluidized bed incinerator developed for the EHTI testing was a joint initiative between Ames Research Center, University of Utah and Johnson Space Center. Though in no way an optimized system at that time, the fluidized bed combustor fulfilled the basic requirements of a resource recovery system. Valuable data was generated and problem areas, technology development issues and future research directions were identified during the EHTI testing.

Waste management is a vital function of spacecraft life support systems as it is necessary to meet crew health and safety and quality of life requirements. Depending on the specific mission requirements, waste management operations can include waste collection, segregation, containment, processing, storage and disposal. For the Crew Exploration Vehicle (CEV), addressing volume and mass constraints is paramount. Reducing the volume of trash prior to storage is a viable means to recover habitable volume, and is therefore a particularly desirable waste management function to implement in the CEV, and potentially in other spacecraft as well. Research is currently being performed at NASA Ames Research Center to develop waste compaction systems that can provide both volume and mass savings for the CEV and other missions.

NASA's future missions to explore the solar system will be long-duration missions and could last years at a time. Human life support systems required for these missions must operate with very high reliability for long periods of time and must be highly regenerative, requiring minimum resupply. Such life support systems will make use of combining higher plants, microorganisms, and physicochemical processes to recycle air and water, process wastes, and produce food. Development of regenerative life support systems will be a pivotal capability for missions to the moon and Mars. One key step in the development process for these systems is the establishment of a human-rated test facility specifically tailored for evaluation of closed, regenerative life support systems--one in which long-duration testing can take place involving human test crews.

A step in the development of advanced regenerative life support systems is to produce simulation models to guide experimentation and hardware development. This paper discuses the development of detailed simulation models of water reclamation processors using the ASPEN PLUS™ simulation program. Individual models have been developed for Vapor Compression Distillation (VCD), Vapor Phase Catalytic Ammonia Removal (VPCAR) and Supercritical Water Oxidation (SCWO). This paper outlines the methodology which is used to complete this work and discusses the insights which are gained by this type of model development. A discussion of how modeling predictions are used to direct future work in modeling and experimentation is also presented. The initial set of modeled processors were VCD, VPCAR, and SCWO. Future work will cover the modeling of other processors. These models will be linked to form subsystem level models, and evaluations will be performed on various configurations.

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.

The crew of the BIO-Plex (Bioregenerative Planetary Life Support Systems Test Complex) will produce most of its food by growing crops. Food growing and processing will make up nearly half the total work load, which is about 46 hours per week per crewmember. This is acceptable for a ground test but leaves little time to conduct an actual planetary mission. Crop harvesting and replanting can be scheduled to occur at ten day intervals if the tests are short or if the crop growth periods are adjusted. All crew activities can be planned for long tests by using replicated ten day schedules.