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Two-week closed habitation experiments were repeated three times using Closed Ecology Experiment Facilities (CEEF) to evaluate the capability of advanced life support systems. The CEEF is a two-manned system. Four crew members, termed econauts, inhabited the CEEF, taking turns at one-week shifts in pairs. Each econaut underwent three habitations. In order to evaluate the state of health of the crew, medical examinations were carried out before, immediately after and two months after the series of habitations. Physical data such as blood pressure, body temperature and body weight were monitored during each habitation. In 2005, though calorie intake and expenditure were well balanced, a temporary reduction in body weight was observed. As a countermeasure in 2006, econauts began their habitation diet one week before habitation to adapt their condition. As a result, total serum cholesterol significantly decreased after the series of habitations.

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.

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.

In order to verify the material circulation design for a Closed Ecology Experiment Facilities, CEEF, the organic element analysis of edible and inedible parts of the major candidate plants (rice, soybean, sesame and komatsuna (Brassica campestris)) has been carried out experimentally and by using food analysis data. In the experiment, rice, soybean and sesame were cultivated by hydroponics and soil culture for this purpose. The organic element analysis data from the food analysis data were made using empirical chemical equations formulated as to major nutriments by Volk and Rummel. The experimental results showed good agreement with those obtained from the food analysis data. Komatsuna has high nitrogen content. Inedible parts of rice, soybean and sesame have almost the same constituent ratio. The edible part of soybean contains five times as much nitrogen as its inedible part. Rice shows no significant difference between the edible and inedible parts.

In the Closed Ecology Experiment Facilities (CEEF), waste materials such as plant inedible parts, feces and urine of animal and human, and garbage are to be decomposed to inorganic materials by a physical and chemical (P/C) process; Wet Oxidation (W/O). It is known that significant part of nitrogen (N) in the waste materials is reduced to gaseous nitrogen (N2) through W/O process. There is also some deposition of minerals such as iron (Fe) and phosphorous (P) through W/O process. Nitrogen Fixation Subsystem (NFS) produces ammonia (NH3) which is one of end products of NFS, from N2 separated from module air and hydrogen (H2) derived from electrolyses of water, and also produces nitrate (HNO3) from a part of the NH3 and oxygen (O2) derived from electrolyses of water. As another end product of NFS, ammonium nitrate (NH4NO3) is produced from the HNO3 and a part of the NH3.

The closed ecology experiment facility (CEEF) has a small positive pressure control system consisting of rubber buffers and a mechanical subsystem. In the present study, effects of small temperature disturbances caused by changes of surrounding conditions on the pressure control system are investigated experimentally and in numerical simulations. Though solar radiation causes a pressure disturbance in the facility, choosing the proper diameter of ducts which connect the rubber buffers to the modules, the rubber buffers can follow fluctuations of low frequency, like daily atmospheric fluctuations and pressure changes caused by temperature control of the facility’s air conditioners, and can cut off those of high frequency due to changes of environmental conditions.