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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.

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) were installed to collect data for realistic estimation of radiocarbon transfer in the ecosystem. Two-week experiments were conducted three times from September to November of 2006, in which two human subjects called as eco-nauts were enclosed and worked in an airtight facility, the CEEF. The eco-nauts were changed after a week from beginning of each experiment. In these experiments, a Plant Module (PM) with 23 crops, including rice, soybean, peanut, and sugar beet, was connected to an Animal & Habitation Module (AHM) which included the eco-nauts and two goats. 91.8-94.6% (by weight) of the food consumed by the eco-nauts and 79% of the feed to the goats (straw, leaf and bran of rice, leaf and stem of soybean, and leaf, stem and shell of peanut) were produced from crops in the PM. Amount of oxygen produced by the crops was more than the amount consumed by respiration of human and animals in these experiments.

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.

Before a series of overall material circulation in an experimental system including crops, animals and humans, technical examinations for the development of a waste processing system were conducted for incorporating the system to the Closed Ecology Experiment Facilities (CEEF). The examinations are intended to validate the function of the carbonization and incineration processing units which were installed in the CEEF in 2006. Using different mock-up samples, examinations have been carried out to verify the function and capability of the whole system, including the waste carbonization processing unit, incineration processing unit, exhaust gas tank and the exhaust gas processing unit. In an examination using filter paper pulp as a mock-up sample, processing time in each unit was checked. The processing times needed for carbonization and incineration processing were 5.7 and 2.6 hours, respectively.

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.

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.

Three 1-week experiments were conducted from September to October of 2005 in which two human subjects called as eco-nauts were enclosed and worked in an airtight facility called Closed Ecosystem Experiment Facilities (CEEF). The test involved connecting a Plant Module (PM) with 23 crops, including rice, soybean, peanut, and sugar beet, to an Animal & Habitation Module (AHM), which included the eco-nauts and two Shiba goats. Although only 34% (by weight) of the food consumed by the eco-nauts was produced by crops in the PM in the first experiment, it was 81% in the second and third experiments. As for feed for the goats, although all was Timothy hay was supplied from outside in the first experiment, all of the feed (rice straw, soybean leaf and peanut shell) was produced in the PM in the second and third experiments. In all these experiments, the crops produced more oxygen than the amount consumed by respiration of human and animals.

In the Closed Ecology Experiment Facilities (CEEF), an artificial ecosystem including crops, Shiba goats, and human inhabitants is to be constructed in order to conduct long-term habitation experiments. For carbon circulation in this artificial ecosystem, CO2 needs to be recovered from the air of animal breeding and habitation rooms using a CO2 separator and to be injected into growth chambers for consumption in crop photosynthesis. Moreover, daily crop yield from the growth chambers needs to be stabilized to drive carbon circulation in the artificial ecosystemwithout huge buffers. Because crops are cultivated in a staggered manner, controlling atmospheric CO2 concentration in the growth chambers at a constant level during light periods throughout crop cultivation is necessary for stabilizing daily crop yield.

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 Closed Ecology Experiment Facilities (CEEF), designed to simulate material circulation, is an artificial closed agricultural ecosystem with plants, humans, and animals. The drying toilet system “DRI-LET®” had been installed in the habitation module as a human waste processor for material circulation by carbonizing. Carbonizing of human waste has advantages in life support systems because it can minimize the total volume and weight of human waste. However, this toilet system releases many gases during processing. In particular, NO2 concentration in the habitation module increased up to 4 ppm when one person used the toilet system. In this paper, we report NO and NO2 behavior in the habitation module during experiments and a method to reduce their concentrations by using NO and NO2 adsorbent.

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.

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.

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 %.

This paper introduces a concept and a design to supply paper products for an earth based Advanced Life Support System (ALSS) test bed and it shows some results of paper production trials on the ALSS using inedible biomass. Rice plants (i.e. straw and roots), and soybean stems were pulped by boiling and/or alkali soaking and a mechanical processing method. Paper could be produced from both and exhibited different characteristics. Paper with quality suitable for hygienic tissue could be obtained and very absorbent paper was also possible. A rapid pulping method without a chemical process was also investigated. A potential for reducing chemical consumption, liquid waste and labor cost of paper production in the ALSS was demonstrated.

Closed habitation experiments are to be carried out using Closed Ecology Experiment Facilities (CEEF) from 2005 to 2009. The last target of duration of closed habitation is four months. Preliminary study and testing have been conducted in order to start the closed habitation experiments. In 2004 as the last year of the preliminary test phase for the 2005–2009 experiments, periodical harvesting from staggered cultivation of 23 crops including rice, soybean, peanut, and sugar beet was continued during 103 days. In order to balance with metabolisms of humans (named as “eco-nauts”) and animals, it is necessary to stabilize production of edible and inedible biomass, CO2 uptake and O2 production of crops. Although biomass production decreased rapidly during first five weeks of the 103-day period, it was relatively stable during last ten weeks. Average major foodstuffs in the harvested edible biomass met the requirement of two Eco-nauts although several minor ingredients were insufficient.

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.