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The establishment of a human-tended lunar base requires an autonomous bioregenerative life support system. Bioregeneration within a Lunar Engineered Closed/Controlled EcoSystem (LECCES) can be realized by integrating humans, plants, animals, and waste treatment subsystems. This integration incorporates physical/chemical and biological waste treatment processes that minimize resupply requirements from Earth. A LECCES top-level system integration model is developed based on human metabolic massflow requirements. The proposed model is presented and its components are discussed.

Conversion of lunar regolith into a plant growth medium is crucial to the development of a regenerative life support system for a lunar base. Plants, which are the core of such a system, are a source of food and oxygen for humans and a sink for carbon dioxide and other wastes. Because of the the shortage of lunar regolith, simulants were used for examining its suitability for plant growth. Dissolution studies of Minnesota Lunar Simulant (MLS), a prepared finely-ground basalt, were conducted to measure solution species, to assess the levels of plant nutrients and toxic elements, and to identify the minerals controlling these levels. MLS weathered in shaker flasks over a 150 d period yielded basic solutions of pH near 9.0 buffered by calcite. Most elemental concentrations were within the range for typical alkaline terrestrial soil solutions.

Exploration of the Moon is the most crucial and decisive step toward human expansion into the vast reaches of space. The Moon is the natural and ideal testbed for determining human capability to survive, function, expand and settle into the space environment. Scientific studies, astronomic observations, and exploitation and utilization of space resources culminating in the establishment of a self-sufficient permanently human-tended lunar base are the goals of lunar exploration. Four development stages in the evolutionary exploration of the Moon are suggested: (1) exploratory; (2) pioneering; (3) outpost; and (4) base. Overall goals and specific objectives, functional requirements, construction conditions, and life support systems requirements needed in each stage are identified.

Long-term human missions in space, establishment of a human-tended lunar base and of a Martian base requires an autonomous life support system. An Engineered Closed/Controlled Ecosystem (ECCES) can provide autonomy by integrating a human module with support plant and animal modules and waste treatment subsystems. Integration of physical/chemical and biological waste treatment subsystems can lead to a viable and operational bioregenerative system through minimizing resupply requirements from Earth. Life support requirements of the human module “drive” the design and operation an ECCES. A top-level diagram for an ECCES was developed based on the human module requirements. The proposed top-level diagram is presented and its components are discussed.

Conversion of lunar regolith into a plant growth medium is crucial to the development of a regenerative life support system for a lunar base. Simulants must be used to study weathering processes and to develop procedures for the conversion of lunar regolith into a suitable plant growth medium because of the shortage of actual lunar materials. Dissolution studies have been conducted for Johnson Space Center Lunar Simulant-1 (JSCLS-1) to assess levels of plant nutrients and toxic elements. Weathering in water for 150 4 in the presence of atmospheric oygen and carbon dioxide, yielded alkaline solutions with pH near 8.8. Concentrations of most plant nutrients were at levels normally considered acceptable for plant growth. However, nitrogen was deficient, and phosphorus was present at levels typical of unfertilized soils. DTPA extracts indicated possible manganese and zinc deficiencies. Solution metals were at concentrations far below those generally harmful to plants.

As space missions become longer in duration, the need to recycle waste into useful compounds rises dramatically. This problem can be addressed through the integration of human and plant modules in an ecological life support system. One of the waste streams leaving the human module is urine. In addition to the reclamation of water from urine, recovery of the nitrogen is important because it can be used as a nutrient for the plant module. A 3-step biological process for the conversion of nitrogenous waste (urea) to resource (nitrate) is proposed. Mathematical modeling was used to investigate the bioreactor system, with the goal of maximizing the ratio of performance to volume and energy requirements. Calculations show that separation of the two microbial conversions into two steps requires a smaller total reactor volume than combining them in a single bioreactor.

Closed ecological life support systems incorporating plants represent the only potential for achieving self-sufficiency in an extraterrestrial biosphere. A model of input/output metabolic mass flow rates for a plant module in an Engineered Closed/Controlled EcoSystem is presented. Wheat crop was chosen as a case study for modeling metabolic mass flow rates. Coefficients for the mass flow rates, for each metabolic element, are determined per unit area of wheat production. The coefficients are utilized to compute the area of edible biomass production necessary to accommodate human food requirements. This model for computing metabolic mass flow rates can be applied for any crop under specified growing conditions.