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The most important CELSS engineering parameters are, in order of decreasing importance, manpower, mass, and energy (1). The plant component is a significant contributor to total system equivalent mass. In this report, a generic plant component is described and the relative equivalent mass and productivity are derived for a number of instances taken from the KSC CELSS Breadboard Project data and the literature. Typical specific productivities (edible biomass produced over 10 years divided by system equivalent mass) for closed systems are of the order of 0.2.

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.

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?

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.

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.

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.

Clothing can constitute a major logistical problem for advanced missions. Current and historical clothing systems for space missions have been assessed, as has the viability of using a washing machine to clean (recycle) clothing. Modern fabrics can reduce the mass and increase the functionality of clothing, including reducing the risk of fire, for all missions. The increased cost of acquisition of even high tech commercial off the shelf (COTS) items is trivial compared to the cost of shipping the clothing and disposing of it as trash. Washing can be cost effective when water is recycled efficiently, provided the mission is long enough. The breakeven time for clothes-washing depends on the specifics of the mission, particularly the mass equivalencies of infrastructure, but is of the order of weeks rather than years.

Solid Waste Management (SWM) requirements need to be defined prior to determining what technologies should be developed by the Advanced Life Support (ALS) Project. Since future waste streams will be highly mission-dependent, missions need to be defined prior to developing SWM requirements. The SWM Working Group has used the mission architectures outlined in the System Integration, Modeling and Analysis (SIMA) Element Reference Missions Document (RMD) as a starting point in the requirement development process. The missions examined include the International Space Station (ISS), a Mars Dual Lander mission, and a Mars Base. The SWM Element has also identified common SWM functionalities needed for future missions. These functionalities include: acceptance, transport, processing, storage, monitoring and control, and disposal. Requirements in each of these six areas are currently being developed for the selected missions.

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.

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.