It is ultimately impossible for life on the Earth to survive in space without the science and technology of human beings. To enable human and life on the Earth of inhabiting sustainably in space environment, we need to create the new system of space science and technology by integrating existing sciences, such as physical science, life science, applied science, social science and art. The action principle of the Japan Society of Microgravity Application (JASMA) states: “We develop science and technology to solve the global problems that our society now confronts, using unique microgravity environment in space.” According to the principle, we carry on integrated research programs that consist of 1) basic research, 2) applied research, and 3) space project. In this paper, the roadmaps of microgravity-applied sciences are overviewed by reviewing the outputs of ISS experiments and a unified program of space environment utilization on the Moon is proposed as a post ISS program.
Fire safety tests of materials used in the international space station have been conducted in normal gravity. However, in the previous researches, flame could spread in lower oxygen concentration in microgravity than in normal gravity. Therefore, it may cause fire hazard to use the ground-based flammability test results for microgravity environments. In the present paper, we modify our previous simplified model by including the effect of boundary layer on the material and compared the result with the parabolic flight experiment. Also we report the flammability limit of NOMEX, the typical flame resistant material obtained by parabolic flight experiments and compare it with PMMA. The results show that the minimum oxygen concentration (MLOC) of NOMEX was about 2% lower than that in normal gravity, and the flow velocity at MLOC is much larger (10~20cm/s) than that of PMMA (6~10cm/s). The feature of the flammability limit of NOMEX was successfully predicted by the modified model with the blow-off test data in forced flow.
Spectral emissivity and constant heat capacities of molten metals (nickel, zirconium, rhodium, and niobium) at their melting temperatures were measured using containerless techniques. Samples were levitated in an electrostatic levitator and the radiation intensities from the molten samples were measured with spectrometers over a wide wavelength range. The spectrometers were calibrated with a blackbody radiation furnace and the spectral hemispherical emissivity was calculated. Then, the total hemispherical emissivity (εT) was obtained by integrating the spectral emissivity over wavelength. Finally, constant pressure heat capacity was calculated using the data obtained from the cooling curve and εT.
Fluid behavior in microgravity (μg) is different from in ground gravity since surface tension, viscous force, and wetting are dominant in g condition. In propellant tank for artificial satellite and future on-orbit spacecraft, sloshing due to disturbance and settling behavior by change of acceleration have to be understood for design of propellant supply system and attitude control system. These fluid behaviors in μg are affected by a dynamic wetting significantly, therefore it is important to understand dynamic wetting which dominates fluid behavior. We observed fluid behaviors in cylindrical containers in microgravity conditions created by drop tower facility, and effect of viscosity and diameter of container on fluid behaviors were investigated. CFD analyses were conducted and these results were compared with experimental results. It was confirmed that numerical model considering dependence of contact line velocity in dynamic contact angle by empirical and theoretical methods provided more reasonable results.