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A mathematical model was developed in order to predict quantities of CO2 and O2 gas exchange, transpiration, biomass production, food production and nutrient absorption by candidate crops in Closed Ecology Experiment Facilities (CEEF) in which material recycling in a controlled ecological life support system (CELSS) is to be made. This model includes effects of physical parameters such as light intensity, air temperature, humidity and atmospheric CO2 concentration on these processes and plant aging effect on these processes. Using results from experiments in which candidate crops were grown under controlled environment and data from literature, mathematical models for each crop was given physiological parameters. Then, changes in biomass and food accumulation, gas exchange and transpiration of each crop with time were calculated.

The Closed Ecology Experimental Facilities (CEEF), is designed to simulate material circulation, and is an artificial closed agricultural ecosystem with plants, humans and animals. The first seven-day air circulated confinement experiments using the CEEF were conducted three times. The experiments included psychological monitoring of two crew members named “Eco-nauts”. Even though there was some trouble with the CEEF regarding the atmospheric gases (which one of the Eco-nauts discovered himself), all three experiments were completed without critical problems and both Eco-nauts maintained a stable psychological status. Through the experiments, it was found that the interior environment of the CEEF could fluctuate within short time periods, and that frequent monitoring by the instantaneous and sensitive Face Scale Test allowed scoring of the Eco-nauts' response to such fluctuations.

The plant system plays roles of edible biomass production, O2 production, CO2 removal, and so on, in bioregenerative life support systems. In order to simulate the edible and inedible biomass production and gas exchange of crops, it is necessary to construct reliable dynamic prediction models for each crop considering not only short-term environmental effects but also its long-term effects, because response of plant system is highly dependent on plant age, plant size, and environmental condition experienced by the plant. Closed Plantation Experiment Facility (CPEF) of Closed Ecology Experiment Facilities (CEEF) has three plantation chambers with artificial lighting system, which has maximum capability for providing PPFD of approximately 1900 μmol·m-2·s-1 for crops at canopy top level in these chambers. Each even-aged population of rice and soybean was grown in each plantation chamber.

In order to prolong the duration of manned missions around the earth and to expand the human existing region from the earth to other planets such as a Lunar Base or a manned Mars flight mission, the CELSS becomes an essential factor of the future technology to be developed through utilization of Space Station. The preliminary SE&I (System Engineering and Integration) efforts regarding CELSS have been carried out by the Japanese CELSS concept study group for clarifying the feasibility of hardware development for Space Station Experiments and for getting the time phased mission sets after Fy 1992. The results of these studies are breifly summarized and thereafter, the design and utilization methods of a Gas Recycle System for CELSS experiments are discussed.

Recycling human and animal excreta is an important part of the proposed Closed Ecology Experiment Facility (CEEF) in Japan. This paper introduces a conceptual design for the waste collection and transfer system. Mineral-rich wastes such as urine and wool grease must be separated from other wastes to recover the minerals. Solids and liquids also require separate handling methods. Our design uses inclined conveyer belts to separate feces and urine. A fluorocarbon polymer coating prevents wastes from sticking to the belt. In-line freezers are used to solidify liquid wastes and retard premature decomposition. A summary of available data on animal excreta is included, but there is a distinct shortage of useful information. This data is insignificant for usual biology or animal husbandry, but is essential for designing the self-contained environment.

In the Closed Ecology Experiment Facilities (CEEF), with integrating the Closed Plantation Experiment Facilities (CPEF) and the Closed Animal Breading & Habitation Facilities (CABHF), closed habitation experiments without material exchange with the outside will be conducted after the 2005 fiscal year. Cultivation experiments of about 30 crops and the integrating test of the material circulation system required for the closed habitation experiments have been performed since 2000 fiscal year. Using data reported in these experiments, material circulation in CEEF is simulated based on the recent operation strategy, and the storage capacity needed for the buffer of an air processing subsystem was estimated. In order for two humans to dwell over 120 days, the storage capacities of the carbon dioxide tank, the oxygen tank, and the waste gas tank in CPEF, and the carbon dioxide tank and the oxygen tank in CABHF are 820 g, 2830 g, 4425 g, 1780 g, and 1792 g, respectively.

The front half of the nitrogen fixation system, which is one of the subsystems of Controlled Ecological Life Support System (CELSS), or NH3 synthesis loop at atmospheric pressure, was studied. The NH3 separation essential in the loop is discussed. The NH3-PSA method was newly developed, since the NH3-PSA was evaluated best among separation methods from the viewpoints of CELSS criteria. It is essential to retain the H2/N2 ratio in the outlet gas the same as that of the inlet gas to the PSA. From the experimental result of PSA a material balance of the NH3 synthesis loop was calculated. Additionally a material balance of the overall process was calculated by assuming some performances in the down stream sections of the NH3 synthesis loop.

Preliminary seven-day habitation experiments without complete closure of the habitation module were performed in the Closed Ecology Experiment Facilities (CEEF) to obtain information for the closed habitation and to prepare for the actual closed habitation experiments to be launched in September 2005. Energy requirements have been estimated for habitant candidates in closed habitation experiments (to be called Eco-nauts). This paper presents the calculations of Eco-nauts' energy requirements using records of life activities during the preliminary experiments and compares them with the expected energy supply from the CEEF.

The Closed Ecology Experiment Facilities (CEEF) can be used as a test bed for Controlled Ecological Life Support Systems (CELSS), because technologies developed for the CEEF system facilitate self-sufficient material circulation. Two experiments were conducted from September 27, 1999 to February 17, 2000 and from September 28, 2000 to February 9, 2001 in this study. In both experiments, rice and soybeans were cultivated sequentially in each chamber, having a cultivation bed area of 30 m2 and floor area of 43 m2, inside the Plantation Module (PM) with artificial lighting of the CEEF. 6 to 8 other vegetables were also cultivated in a chamber, having a cultivation bed area of 60 m2 and floor area of 65 m2, inside the PM with natural lighting in the first experiment and the second experiment. In both experiments, stable transplant and harvest of each crop were maintained during approximately one month, after approximately 3-months preparatory cultivation.

Many research activities relating the environment control and life support systems to be used in space have been conducted and continued in Japan since 1982 in order to obtain his own manned flight technologies for future Japanese missions. Research and development activities are able to be divided in two phases according mission scheduling such as JEM development to be used in International Space Station now going on and the future Japanese space infrastructures, for examples, Japanese Space Station and Lunar Base. Temperature, humidity, total atmospheric pressure and partial pressure of oxygen and carbon dioxide, necessary for all living things, are to be controlled by the environment control function.

Lunar base construction study has been conducted under the sponsorship of many Japanese industries to amend the man tended lunar outpost study carried by NASDA. Permanent lunar base construction is to be constrained by the ability of the usable transportation system carrying the basic modules composing lunar base itself. Based upon the experiences of Antarctic Research Expedition and of designing International Space Station now going on it was assumed the initial permanent lunar base has to be composed of two habitats and one power module for letting possible to alive 8 crews, and has to be expanded by adding three or four modules in every year for improving the easiness of livingness. In early stage of construction, crew members have to live and work using only two habitat modules with getting the electric power from power module, therefore the minimum self support functions except the food and oxygen supplying have to be attached to the habitat modules.

A linear programming model has been constructed to develop a cultivation plan for habitation experiments using a two-person crew in Closed Ecological Experiment Facilities (CEEF), which is an earth based integration demonstration test bed of Advanced Life Support System (ALSS), under constraints such as a limited cultivation area and various nutritional requirements. The optimized area was 129.14 m2. According to the results, the optimized cultivation plan was then implemented in a habitation experiment in the CEEF during FY2004 with some modification to meet requirements from menu formulation. Results of the cultivation experiment, also during FY2004, showed feasibility of the plantation plan in the view point of nutrition supply, though errors between expected and observed productivities varied from −37 % to +267 %.

Rating of daily amounts of CO2 and O2 exchange of crops, animals and humans to be involved in the long-term habitation experiments using the Closed Ecology Experiment Facilities (CEEF) were carried out. Daily amounts of the CO2-absorption and O2-generation of crops including rice, soybeans and other 27 vegetables were estimated from data obtained from a sequential crop cultivation experiment conducted from August to December of FY2001. Daily amounts of O2-consumption and CO2-expiration of two female Shiba goats to be involved were estimated based on gas exchange determination conducted in FY2002. Daily amounts of CO2-expiration and O2-consumption of two persons to be involved were estimated based on correlation between respiration rate and heart rate, heart rate data during the simulated habitation in the CEEF and a tentative work schedule.

The closed ecology experiment facilities(CEEF) are comprised of an animal breeding & habitation module, plant module, and a geo-hydrosphere module(currently being established), which are composed of physicochemical devices to allow almost all the material to be circulated. Partial test operations are now in progress with these kinds of equipment, and cooperative operations between an animal breeding & habitation module and plant module are expected to be started in the near future. Balance of the material and equipment performance as the whole of the system are being tested, and material circulation in a variety of operation modes is being examined. Keeping such a situation in mind, analysis is made in this report for material circulation in the plant module by itself for operations based on the equipment design data.

Materials circulating in a closed ecological system are classified as metabolic ones and nonmetabolic ones. Nonmetabolic substances relate to environment constituents and cultural activities. Treatment of these materials are discussed from a view point of CELSS concept. The closed system, CEEF, will be constructed in Japan in the near future. CEEF is an experiment facility with processing capacity of two adult persons, consisting of a plant module, an animal module, a habitat module and supporting facilities for the three modules. The supporting facilities are composed of artificial processors of gases, waters and wastes. The plant module has artificial and natural lighting cultivating sections.

IES (Institute for Environmental Sciences) is now constructing CEEF at Rokkasho, Aomori, Japan. The simulation for material flow is made based on a system model of CEEF, which includes one person and 7 plant species of Rice, Soybean, Komatsuna, Sesame, Tomato, Potato and Buckwheat. In this simulation software, plants, human and their support systems are mathematically defined and material flows such as O2, N2, CO2, waters, fertilizers and organic matters are computed. This software simulates only material flow and but does not simulate thermal dynamics of the environment. The simulation result showed reasonable material flows in a closed system.

We propose a new recovery system for NaCl from human urine. The system has an electrodialysis (ED) part and a crystallization part. Separation and concentration characteristics of the system are discussed for fundamental experiments of the ED and crystallization parts. Concentrated NaCl-KCl mixed solution is obtained using the ED process from simulated oxidized urine and sweat which include Ca2+ and S042- ions. Then, the crystallization process is used to separate about 80% of the NaCl from the ED treated solution. The experimental studies indicate that the mineral recovery system we proposed can recover NaCl from waste water of a CEEF.

A unique recovery system for NaCI (salt) from urine, which consists of electrodialysis (ED) and crystallization processes is proposed. The possibility of the mineral recovery included in urine is shown in a previous report. To improve the purity of the produced salt, pH control is needed as a pretreatment. By controlling pH of the feed solution to about 10, multivalent ions such as Ca2+ and Mg2+ are crystallized as phosphate solids which can be separated by filtration. As well as raising the NaCI purity, this controls scaling b y multivalent ions.

The recovery of important minerals, salt (NaCI) and potassium (K), in a closed system, namely CELSS is discussed. NaCI is needed for humans, but is potentially harmful to plants. Salt is recovered after wet oxidation of urine. Since Na and K have similar chemical and physical properties, their recovery or separation may require sophisticated methods. Na, CI and K ions are separated from other ions by electrodialysis with univalent selective ion-exchange membranes and then NaCI is obtained separately by a crystalization process. Preliminary experiment on crystalization of NaCI-KCl mixed solutions showed a good separation result.

The Nitrogen Fixation System (NFS) which produces ammonia and nitric acid from nitrogen and water has been developed. The NFS is one essential part of material circulation system of the CEEF (Closed Ecological Experiment Facility) the first Japanese CELSS experiment facility. Basically, physico-chemical and some new technologies are utilized as elemental processes in the NFS. Low pressure ammonia synthesis, ammonia enrichment with PSA and water electrolysis with SPE are such new technologies. We designed and installed the NFS as a subsystem of CEEF. The capacity of the NFS is 125g/day as fixed nitrogen. First operation of NFS is expected to be done early fiscal year of 1996 in CEEF.