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About two dozen different mission segments can be identified for the various missions encompassed by the Vision for Space Exploration (VSE). Clearly, many crewed space vehicles will be needed on the several decades to be spanned by a return to the Moon, a Lunar outpost, and a human mission to Mars. A number of different vehicle types will be needed to operate in the different environments. Furthermore, technology will change overtime. This paper addresses two issues: how many types of life support system will we need for these diverse missions, and how many copies of each will we need? A manifest has been developed for discussion. Based on this manifest, numbers of vehicles have been identified. Possibilities for reuse and of impacts from commercial operations will be considered. Vehicles will be needed for launch from and landing on the Earth, the Moon, and Mars. Vehicles will be needed for transit segments. Surface habitats will be needed.

Current projections for the crop mix in the Bio-Plex and the future Lunar bioregenerative life support system indicate that without supplemental oil production, the crew's diet will be extremely low in fat, with little refined oil available for food processing or preparation. Although soybeans, peanuts and dwarf brassica (similar to canola) have been suggested as oil crops, each one poses significant problems either in horticulture, harvesting, productivity or byproduct utilization. An alternative to plant oils is “single-cell oil” or SCO. Lipid-accumulating “oleaginous” micro-organisms may accumulate up to 60% of their dry weight as triglycerides. Their high growth rates enable them to synthesize lipids with far greater productivity than higher plant systems. The current top candidate species for use in a bioregenerative system is a yeast, Cryptococcus curvatus.

Mass transfer of plant and human nutritional minerals in a Biological Advanced Life Support (BALS) were simulated to determine if deficiencies or toxic levels of minerals would develop in plant or human diets in a BALS. Scenarios of mineral recovery were simulated to determine if harmful levels of minerals develop in the human diet and in the nutrient solution, how long the nutrient solution could be used before toxic concentrations exist in the solution, and the level of mineral resupplied needed to support a BALS. Results indicated that the human diet is deficient in some mineral levels, and contains excess, but not harmful, levels of many minerals. Plant deficiency levels and the accumulation of toxic concentrations of minerals in the nutrient system were dependent on the recovery of minerals in the bioreactor

Viability of bioregeneration for life support – providing food, water and air – on long-duration missions depends critically on cost of the plant habitat and on plant productivity in this habitat. Previous estimates, e.g. Drysdale and Wheeler, 2002 of both cost and productivity have been made using existing chamber designs, in particular the BIO-Plex (Bioregenerative Planetary Life Support Systems Test Complex) Plant Growth System intermediate design review (IDR) design. However, this design was developed for a terrestrial testbed, and is not optimized for use in space, much less for a particular space environment. Nor has productivity been determined experimentally for this configuration. We have examined this design and updated it for use on the Moon, with 709-hr days (light / dark cycles), using both natural and artificial light. Each system within the plant habitat was evaluated and modified to some extent for the desired use.

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 second-generation system model has been developed to account for the movement of carbon, hydrogen, and oxygen through the various life support system components. It accounts for edible and inedible biomass and the water content of plant materials, and models various crops based on growth and transpiration rate tables, including multiple overlapping crops of the same or different species. It also calculates mass, volume, energy use, heat rejection, and manpower required for each component, including varying power use, heat rejection, and manpower as a function of the crop, and equivalent mass (EM) for each cost factor and for the system. Results are displayed graphically. The model was developed using G2, a commercially available modeling package. Enhancements are under consideration to improve the modeling of waste management and to account for minerals and variations in crew metabolism.

Controlled Ecological Life Support System (CELSS) technology is critical to the Space Exploration Initiative. NASA's Kennedy Space Center (KSC) has been performing CELSS research tor several years, developing data related to CELSS design. We have developed OCAM (Object-oriented CELSS Analysis and Modeling), a CELSS modeling tool, and have used this tool to evaluate CELSS concepts, using this data. In using OCAM, a CELSS is broken down into components, and each component is modeled as a combination of containers, converters and gates which store, process and exchange carbon, hydrogen, and oxygen on a daily basis. Multiple crops and plant types can be simulated. Resource recovery options modeled include combustion, leaching, enzyme treatment, aerobic or anaerobic digestion, and mushroom and fish growth. Simulation results include printouts and time-history graphs of total system mass, biomass, carbon dioxide, and oxygen quantities; energy consumption; and manpower requirements.

The computer model described previously [1] has been used for Lunar bioregenerative life support system (BLSS) modeling. Critical factors include the supply scenario (closure, consumables, and spares), startup scenarios, energy cost, mission duration, and policy on allowable dumping of trash. A BLSS will support closure of all life support functions. However, startup may require some time before all support is available. Under some scenarios, closure of water is achieved at about one month, oxygen/carbon dioxide closure at two months, and food closure at three months after the first harvest of food staples. Mineral closure is less critical due to the lower masses involved, particularly of micronutrients, and may not be closed until large numbers of people are to be supported for long periods of time. Alternative startup scenarios include physico-chemical support during startup, remote startup, provision of commodities by supply during startup, and ramp-up of base manning.

This paper addresses a number of construction types and the implications of advanced life support (ALS) system constraints. Space habitats have a number of requirements in common, but are heavily driven by the mission, in particular by the operational environment. Delivery or local manufacturing constraints must also be considered. Life support is one of the primary functions of a habitat, and will be one of the major drivers of the habitat design. Life support will involve a significant commitment of mass, energy (and so heat rejection), and manpower. Different options for life support will require different amounts of these resources. To compare scenarios, equivalent mass (the mass cost of each resource) is used.

Advanced life support systems require computer controls which deliver a high degree of reliability and autonomy and meet life support criteria. Such control systems must allow crewmembers on long-term missions to perform their scientific and engineering duties while minimizing interactions with life support systems. Control systems must be the “brains” of life support systems providing air, water, edible biomass, and recycling services. They must establish and maintain life support components in an optimized manner, providing self-sufficient infrastructures independent of Earth-based resupply. The CELSS (Controlled Ecological Life Support System) Breadboard Project has implemented such a computerized component of a future mission. The Universal Networked Data Acquisition and Control Engine (UNDACE) is the software interface between humans and hardware controlling plant growth experiments.

The reliability of biological life support systems, critical for long-duration human space missions, has been questioned. We propose that properly engineered biological components are inherently reliable, and support this view with data from nine years of operation of the CELSS Breadboard Facility (CBF) at Kennedy Space Center. Reliability problems in a bioregenerative life support system will generally be caused by support system failures, they will generally not be catastrophic, and the crew will have ample time to respond. Thus, biological system reliability can be good, and the impact of low component reliability would generally be to increase system cost rather than to risk mission failure.

Plant lighting will be a significant fraction of the overall costs of a bioregenerative life support system on the Moon. Equivalent mass (EM) for lighting can exceed 35% of the system total with all-electrical lighting. In this paper, variation of cost factors related to lighting is addressed for various options including fluorescent, high-pressure sodium, LED, and microwave lamps. An attempt is also made to quantify the cost of using sunlight, considering collectors, optical fibers, and diffusers. The results show that use of sunlight is important in reducing cost for a lunar base because of the difficulty of heat rejection with electrical lighting during the lunar day.

Most work on food production for long-duration missions has focused either on biomass production or nutritional modeling. Food processing, while not a basic life support technology, has the potential to significantly affect both life support system performance and the crew's quality of life. Food processing includes the following tasks: Separation of edible biomass (food) from inedible biomass Conversion of inedible biomass into foodstuffs (optional) Processing of foodstuffs into convenience ingredients or storable forms Storage management for locally produced foods and foods supplied from Earth Cooking and serving of fresh and stored foods Management of wastes and leftovers Cleaning and maintenance of equipment Questions to be answered in design of a food processing system include: What processing and labor-saving equipment is required, and with what capacity? How must earth-based processing technology be adapted for hypogravity?

Food processing will have a significant effect on both system performance and crew habitability on long-duration human space missions. To maximize habitability, the food processing system must be able to utilize available food items for producing a palatable and diverse menu, while minimizing equipment, consumables mass, and manpower requirements. The authors' goal was to minimize the equivalent mass cost (as defined in earlier work) of the food processing system under constraints of nutritional adequacy, variety and hedonic acceptability. In a companion paper, we have developed a concept for organized analysis of food processing at a Lunar or planetary station. In this paper, we propose a way to optimize the cost-effectiveness of this concept for a Lunar base. A four-man ten-year Lunar base was assumed for performing this analysis, based on previous work by Drysdale on regenerative life support systems.

This paper presents background information and describes operating experience with Mars Base Zero, a terrestrial analog of a Mars base situated in Fairbanks, Alaska. Mars Base Zero is the current stage in a progression from a vegetable garden to a fully closed system (Nauvik) that the International Space Exploration and Colonization Company (ISECCo) has undertaken. Mars Base Zero is an 80 m2 greenhouse, with 18m2 of living space attached. The primary goal is to determine the necessary size for Nauvik in order to support one to four people using current ISECCo techniques for growing food crops. In the spring of 2004 Mars Base Zero was planted, and in the fall of 2004, one subject, Ray Collins, was closed in the system for 39 days. The data from this closure indicates that, using ISECCo cropping techniques, Nauvik will need 150 m2 of crop area to support one person. While problems were encountered, the minimum goal of 30 days closure was exceeded.

Clothing accounts for a surprisingly large quantity of resupply and waste on the International Space Station (ISS), of the order of 14% of the equivalent system mass (ESM). Efforts are underway in the ISS program to reduce this, but much greater changes are likely to be possible and justifiable for long duration missions beyond low Earth orbit (LEO). Two approaches are being assessed for long duration missions: to reduce the mass of the wardrobe through use of lighter fabrics, and to clean clothing on board for reuse. Through good design including use of modern fabrics, a lighter weight wardrobe is expected to be feasible. Collateral benefits should include greater user comfort and reduced lint generation. A wide variety of approaches to cleaning is possible. The initial evaluation was made based on a terrestrial water-based washer and dryer system, as this represents the greatest experience base.

A summary of waste processes and waste process data is presented in the context of mission equivalent system mass. Storage, size reduction, drying, aerobic and anaerobic biodegradation, chemical oxidation, pyrolysis, and post processing are evaluated in the context of probable long-duration missions beyond LEO, and the probable quantities and types of wastes and of the other on-board systems. An assessment of the waste systems described in the ALS Reference Missions Document is presented, and rationale for some changes to these systems is provided.

Three significant problems with food supply in bioregenerative lifesupport systems are addressable through use of fermented foods. The quantity of inedible and marginally edible biomass can be reduced; the hedonic quality of the diet can be enhanced; and food storage constraints can be relaxed due to the superior keeping qualities of fermented products. The authors have assessed potentially available materials and fermentation processes used worldwide, to identify promising food fermentations for use in lunar and planetary stations. Conversion of inedible biomass into acceptable food may include hydrolysis of waste biomass to produce sweeteners and acidulants; fermentation of physically fractionated biomass such as leaf protein isolates into acceptable foods; mushroom cultivation on agricultural residues; and conversion of volatile fatty acids produced during waste treatment into edible microbial biomass.