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Human activities in space must include life in a confined, artificial and isolated environment. We investigated the mental and physiological status of four crewmembers undergoing repeated seven-day habitation in an advanced life support system. In order to monitor the psycho-physiological stresses, saliva cortisol and urinary adrenaline were sampled and visual-analog scale was serially recorded. As a result, saliva cortisol and urinary adrenaline levels were higher in pre- and post habitation. Psychological scales showed a relatively relaxed mood during habitation, indicating that the crew experienced stress in the pre- and post seven-day habitation periods. The periods of environmental change such as those pre-and post habitation seem to be critical for monitoring the health of crew performing analogous missions.

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.

The CEEF (Closed Ecology Experiment Facilities) was constructed for collecting data on carbon transfer from the atmosphere to crops, livestock and humans by conducting material circulation experiments, including the habitation of humans and animals and growing crops which supply food and feed, within a closed environment. The main objective of the CEEF project involves understanding the transfer of radiocarbon in the environment via experiments using stable carbon isotopes. On the other hand, the project is also a good example demonstrating human life in ecosystem material circulation. Many people visited and toured the CEEF and the project has been introduced by the media. The candidate inhabitants, who were selected for the project following medical and psychological testing, are called “eco-nauts”. The CEEF project was introduced and eco-nauts participated in events with the intention of educating the public on the human impacts on an ecosystem made by a science museum.

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.

It is necessary to develop a small positive pressure control system for the closed ecology experiment facility (CEEF) to protect against over-differential pressure loading. In the present study, a numerical method was developed to calculate the quantity of state of the closed module, which is fitted with rubber buffers, for the small positive pressure control system. Experiments to examine the pressure change of the closed module were carried out at CEEF. Comparison of calculated and experimental results showed that the present dynamic simulation is suited to estimating the quantity of state of the closed module.

The Closed Ecology Experiment Facilities (CEEF) have been under construction in northern Japan since 1994. These facilities contain the Closed Plant Experiment Facility (CPEF), as well as other facilities, in all of which, Controlled Ecological Life Support Systems (CELSS) research and development can be conducted. The CPEF includes two Plant Cultivation Modules (PCMs), which contain a PCM consists of three 30m2 closed cultivation rooms illuminated solely by lamps and a 165.1m3 preparation room, and a PCM consists of a 60m2 closed cultivation room illuminated by natural light and supplemental lamps and a 88.8m3 preparation room, and a Material Circulation System (MCS). Measured rate of air exchange between a 30m2 cultivation room and the preparation room was 0.48% hour-1, and that for a 60m2 cultivation room was about 0.11% hour-1. Air leak rate of the PCM as a whole was less than 0.01% hour-1 under isothermal and equal pressure condition.

The Closed Ecology Experiment Facilities (CEEF) were installed to collect data for estimation of transfer of radionuclides from atmosphere to humans in the ecosystem. The first target among the radio-nuclides is 14C. In order to validate function of material circulation in an experimental system constructed in the CEEF, circulation of air constituents, water and materials in waste was demonstrated connecting the Closed Plant Experiment Facility (CPEF) and the Closed Animal and Human habitation Experiment Facility (CAHEF) of the CEEF, since 2005 to 2007. The CPEF has a Plant Cultivation Module (PCM), which comprises of three plant chambers illuminated solely by artificial lighting, one plant chamber illuminated by both natural and artificial lighting, a space for preparation, and an airlock, and a physical/chemical material circulation system.

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.

For validation of operation schedules for the Closed Ecology Experiment Facilities (CEEF), development of the CEEF behavioral prediction system (CPS) has been started. The CPS will be simulated using the CEEF operation schedule. The CPS will gather data on quantities of materials in each component of the CEEF and operational status of each component at the start of the simulation, and configure them as the initial conditions of the simulation. For requirements of experiments, the simulation program for the CPS should be easy to adapt for changes of components and object materials. Because the CEEF is a nonlinear system, available period of the simulation is important. A flexible algorithm for the changes was developed. The simulation was available for three days to validate.

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.

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.

System configurations of water recycling for space use have been continued through theoretical and experimental studies. The water recycling system plays a central role in a Closed Ecological Life Support System (CELSS) which offers necessary environment and life styles in closed environment such as space stations, lunar bases, etc.. Membrane technology is a possible candidate for purifying waste water produced by crew use facility, plant cultivation facility, etc. In considerations of the system compactness realizing energy saving, membrane distillation has been revealed to be a suitable purification process. Ground experiments has been performed using membrane filtration processes and membrane distillation process. Thermopervaporation technology with hydrophobic membrane is utilized in the distillation process. The energy saving is achieved by thermal return of condensation energy.

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.

Closed Ecology Experimental Facilities, CEEF, is designed to regenerate everything required for living, such as air, water, and food. Researchers called “econauts” play a crucial role in maintaining the system in good order. CEEF must involve confinement, which is one of the major factors responsible for deterioration in crew health and performance. Two econauts repeated 7-day habitation in the CEEF 3 times in 2005. Blood cells, hormones and mood status were analyzed. Although clinically no problem, changes of mood status and a stress hormone correlated in an econaut. Characteristic changes were observed in leukocyte ratio. These data are essential in considering the effects of forthcoming long-term habitation in CEEF.

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.

In FY2005, the first series of seven-day closed habitation experiments was conducted using the Closed Ecology Experiment Facilities (CEEF). The operation period of CEEF is planned to be extended to four months by FY2009. The CEEF is a two-manned system. The habitants, called “Eco-nauts”, are responsible for operating the system as a part of an artificial environment. Therefore, their continuous health checks are very important to the success of the habitation experiments. To check their health condition, medical examinations were carried out before, right after and two months after the series of experiments. During each experiment, physical data were obtained and evaluated by medical doctors using a web-video-meeting system. The primary objective of this study was to verify if the schedule and examinations selected for the health check of the Eco-nauts were successfully carried out.

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.

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.

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.