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A regenerative Air Revitalization system has been developed by JAXA. Its major assemblies are a CO2 concentration assembly which contains membrane dryers to remove humidity and zeolite to remove CO2, a CO2 reduction assembly, and a water electrolysis assembly to which water is supplied in the vapor phase through molecule-size pores in a NAFION membrane rather than as liquid to solve the problem of gas-liquid separation in microgravity conditions. A small satellite mission using a subscale air revitalization system (for 1/10 person) is planned as an orbital demonstration of solving microgravity-related problems, interface problems between assembly, compaction problems and saving energy design. A small satellite is used because it has a greater chance of being selected for flight than ISS experiments, and it will be useful for mission assurance to perform small satellite experiments before an ISS manned mission.

A conceptual model of a life support system which circulates material using a physicochemical treatment has been designed. This self-contained partially circulated life support system, called SEPAL, comprises a water electrolysis system using a PEM (Polymer Electrolysis Membrane) and solar collector for a Sabatier reactor. The lack of buoyancy in microgravity causes liquid-gas separation and interferes with conventional water electrolysis. This problem can be solved by supplying water in the vapor phase through molecule size pores in the NAFION electrolysis membrane. This new system connects to a Sabatier reactor, which provides the water vapor for the electrolysis system. This paper describes test results of the main system elements and preliminary test results of the oxygen and hydrogen production system. With a small satellite making use of surplus lifting capacity, the experiment is proposed to demonstrate this circulated life support system.

A series of experiments to evaluate performance of catalysts for CELSS System Wet-oxidation process has been carried out. Data obtained from the experiments show that the noble metal selected for the catalyst gives a good performance in oxidizing Organic Carbon and Organic Nitrogen. The data also show that a catalyst with certain amount of the metal (wt%) shows maximum efficiency in the oxidation; in addition, a catalyst with a different amount of metal gives good performance in producing high quality fertilizer.

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.

As a CO2 removing and recovering technology, the solid amine utilized as a vacuum desorbing type was developed. The evaluation experiments to measure fundamental characteristics of this material was conducted using the dry air and as the results, the high adsorbing rate, 10 wt% for short period and 7 wt% for long period was obtained and also 7 wt% of adsorbing rate can be expected for the operation of desorption temperature of 80 °C. High accuracy thermobalance device so called thermogravimetric analyzer was utilized to measure adsorption and desorption values of CO2.

Conceptual studies of closed ecological life support systems (CELSS) carried out at NAL in Japan for a water recycle system using membranes1) are reviewed. The system will treat water from shower room, urine, impure condensation from gas recycle system, and so on. The H2 O recycle system is composed of pre-filter, ultrafiltration membrane, reverse osmosis membrane, and distillator. Some results are shown for a bullet train of toilet-flushing water recycle equipment with an ultrafiltration membrane module. The constant value of the permeation rate with a 4.7m2 of module is about 70 1/h after 500h of operation. Thermovaporization with porous polytetrafluorocarbon membrane is also proposed to replace the distillator.

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.