n 2003, the experiment was operated aboard the space shuttle Colunbia, STS-107 for the study on the development and swimming behavior of Medaka fry under microgravity in space1). In this experiment a closed ecological system was prepared based on the ABS, Autonomous Biological System2-5） and used to maintain the life of Medaka eggs and hatched fry during flight mission (16 days). It provided mechanically quiet enviroment and was very useful to study the behavior of animals under microgravity. In order to expand the utility of the closed ecological system for space experiment, we conducted studies aiming at designing a closed ecological system to maintain a long-term life support for the least killifish Heterandria formosa. We report the preliminary results of the study, focusing on the effect of biological as well as chemical factors involved in ecological system. According to the evaluation of the life-support performance in terms of the survival, growth, and activity of the fish over 30-day periods, we concluded that the basic design verified in this study would be useful for long-term life support systems for fish. Microgravity environment in space has been recently utilized as the field to inverstigate the gravitational biology. Small-packaged life support systems would be applicable to biological transport through space.
Temperature increases in plant reproductive organs could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions without adequately controlled environments in closed plant growth facilities. The thermal situation of the plant reproductive organs as affected by gravity levels of 0.01 and 1.0g for 20seconds each during parabolic airplane flights was determined under different light intensities in order to make an estimation of temperature increases in the reporoductive organs under microgravity in space. Thermal images of reproductive organs of rice, wheat and tomato were captured using infrared thermography. Temperatures of glumes of rice and wheat and anthers of tomato increased by 1.1, 0.7 and 0.4°C, respectively, over 20 seconds as gravity decreased from 1.0 to 0.01g at an irradiance of 150W-2. Restricted free air convection under microgravity conditions in space would cause the aberration of the reproductive growth of plants by retarding heat exchanges between the reproductive organs and the ambient air.
This paper presents the modeling of a semi-closed system for space colony type space plantation incorporating heat balance and growth curve (Mitscherlich-Bertalanffy curve). In this model, environments such as atmospheric composition, pressure, gravity and day/night cycle are assumed to be the same as on the earth. The plants growth is taken as a function of temperature, and the harvest would be gathered when the ear weight computed with translocation rate of dry matter from vegetative organs to panicle reaches a regulated value. Under these conditions, a simulation program was coded by C-language. According to this simulation system, 1) the temperature of plantation determined by louver open/close temperature2) the fastest plants growth is simulated in the present model. In the future, it is necessary to adjust the modules of growth curve for improvement more realistic food production..
After the completion of the ISS program, the main arena human space activities could move from low-Earth orbit to the Moon in the future. In preparation for such development, JAXA cosiders a future ‘‘international human lunar base’’that might be developed as the place where Japan could fully utilize, maintain and further develop its capability for conduction human space activies. Since the moon is a test-bed for Mars, permanent lunar bases are a logical outgrowth of initial lunar exploration. For brief visits, the lunar base requires only stored oxygen and water, but a permanent lunar base must recycle oxygen and water to reduce transporatation costs. These kind activities will give a great suggestion to sustainable society. A conceptual model of a life support system using physicochemical treatment to circulate the material has been designed. The carbon dioxide in the atmosphere which is exhaled by astronauts is separated and concentrated with zeolite. A gas Mixture of carbon dioxide and hydrogen is supplied from one side of the Sabatier reactor. The gas gose through the reactor and is heated, then the first Sabatier reaction occurred. The unique poit of this new water electrolysis system is suitable to connecting Sabatier reactor because of vapor which is generated by Sabatier reaction could directly electrolyze without condensation module. This paper describes test results of the main system elements and preliminary test results of the oxygen and hydrogen production system..
Manned Mars exploration at a large and long scale inevitably requires recycle of materials to support human life on a distant isolated outpost. A conceptual design is developed for Martian agricultural system based on biologically regenerative functions. Environment in a green house dome will be maintained at sub-atmospheric pressure with proper partial pressure of oxygen and other gas species. Photosynthetic conversion of carbon dioxide and water to oxygen and biomass is the major driving mechanism for habitation on Mars. Water recycle, at a quantity required for human life, can be made by respiration of plant leaves. It should fully utilize a solar energy received on the Martian surface for the photosynthetic reaction. Sub-surface water and atmospheric carbon dioxide mined on Mars should be also associated with the plant cultination system. We selected rice, soybean, sweet potato, and green-yellow vegetable for the core food materials in space agriculture. From nutritional viewpoint, animal origin material should be supplemented to the diet with lipids, including cholesterol, vitamin D, and B12. Insect eating is proposed for the best use of the limited resource available for space agriculture. Silkworm and hawkmoth pupa are candidate for this purpose. Co-culture of rice, Azolla (aquatic fern), and loach fish is promising as well. One of the core technological functions in concept is hyper-ther-mophilic aerobic composting bacterial ecology. It plays a role of processing human metabolic waste and inedible biomass and of converting them to fertilizer for plants cultivation. One of the characteristics of the technology is the processing temperature high at 80-100℃. The quality of the compost has been shown essential to create a healthy regeberative system. In the materials recycle loop, handling of sodium, which is required for human physiology but negatively affects on ordinary plant growth, is another challenge in space agriculture. Cultivating salt accumulating plant species, such as ice plant, or harvesting potassium made by marine algae is promising candidate for this. Space agriculture, with our perspective from Japan and Asia, might be beneficial for solving the global problems of food shortage and loss of agricultural land at increasing human population.