As most of large-scale international joint projects, participation of Japan to the Space Station program proposed by the United States of America (US) was initiated by a political decision made by US President Ronald Reagan and Prime Minister Yasuhiro Nakasone in a socalled Ron-Yasu talk. This project, later called ‘Program’ took place in 1982 as a post-Shuttle project, and the completion of the Space Station was targeted in 1992, which was the 400 anniversary of Columbus discovery of the new continent. In addition to Japan, European Space Agency (ESA) and Canadian Space Agency (CSA) participated. In this article, based on the author’s experience spent at the Space Station Program Office in Science and Technology Agency (STA) from 1985 to 1986 and follow-on activities until now, an overview of the International Space Station (ISS) and manned space activities of Japan will be presented with emphasis on including story of hard negotiations among participating countries, and also between National Aeronautics and Space Administration (NASA) Head Quarters (HQ’s) and field centers. Transition of the names of the space segment of this program may symbolize political influences. Furthermore, participation of Russia after collapse of the Union of Soviet Socialist Republics (USSR) gave a huge impact on the operational aspects of the ISS. We should observe carefully some political implications of space activities in addition to scientific and technical aspects of the venture.
In order to better understand alloy electrodeposition processes, it is essential to isolate the various phenomena involved in film formation. One important aspect in this context is the natural convection occurring in electrochemical cells, observed in the presence of gravity and due to the change in electrolyte density upon electrode reactions. These convection patterns can be minimized by the use of horizontal electrodes, with the cathode on top and facing down. Using this geometry and comparing with a number of other cell configurations, we have observed that the suppression of natural convection leads to more uniform nucleation and tighter composition distribution in Cu-Zn-Sn ternary alloy films. Experiments in a flat cell on alloy dendrite growth show that the most stable growth is again in the top cathode configuration; alloying Ag or Ni with Cu leads to more dense dendrites, increase in tip splitting occurrence and in some cases to the destabilization of dendrite formation, leading to dense and compact films.
A multifunctional X-ray radiography device for parabolic flights and lab-based research is presented. Based on the technology demonstrator X-ray radiography facility DIXI for the Materials Science Laboratory aboard the International Space Station, the full 90◦ tiltability of the facility enables to change the gravity vector with respect to the sample orientation, providing the tunability of the impact of the gravitational force on the investigated processes. The acronym X-RISE - X-Ray Investigations in Space Environment - unifies our research activities by utilizing a X-ray micro-radiography facility for different experiment classes with the need for microgravity environment namely solidification research, diffusion experiments, and the dynamics of granular matter upon compaction. A commercial actively pumped microfocus transmission X-ray source by Viscom AG delivers up to 20W X-ray power at 100 kV acceleration voltage. It is combined with different experiment cartridges and detector modules. The facility is classified as a fully-protected radiography equipment according to German and French radiation safety laws. Besides its use aboard parabolic flights it is also a powerful terrestrial research facility. The technological possibilities of X-RISE for material science research are presented within this paper. Moreover examples of recent parabolic flight experiments focusing on different science areas are presented to highlight the capabilities of this facility.
Marangoni Convection transits from laminar to oscillatory flow under the certain temperature difference. Recently, it is shown that the transition condition is significantly affected by the heat transfer at the free surface. It should have occurred that the driving force is changed as a result of the surface temperature variation due to the surface heat loss. Marangoni convection induced in a half-zone liquid bridge is observed to investigate the relation between the surface temperature distribution and onset condition of oscillatory flow with changing relative temperature range of liquid bridge against the ambient temperature. Critical Marangoni number is clearly reduced in larger heat loss. In this regime, the surface temperature distribution is also changed
In the Soret-Facet performed on the International Space Station, the Soret coefficient ST for salol/tert-butyl alcohol was measured by using a two-wavelength Mach-Zehnder interferometer. The temperature difference between the sides of the solution was set to 10°C so that its mean temperature was 45°C. The refractive index changes in a narrow observation field were measured by using a charge-coupled device camera. We improved the interference fringe analysis used to determine the refractive index changes by determining the interference fringe shifts in a wide area of the solution rather than in the narrow observation field. The interference fringe shifts outside the observation field were measured by moving the field of view and comparing the interference fringe positions. The fringes were found to shift linearly in the wide area. Then, the values of ST in the observation field and the wide area, STnarrow and STwide, respectively, were determined based on the interference fringe shifts. The measurement error δ(ST) was caused by the standard deviation of the slopes of the fit lines, and values of δ(ST)narrow = δ0.34 K-1 and δ(ST)wide = δ0.024 K-1 were obtained for the observation field and the wide area, respectively. Based on the fit lines, which satisfied two constraints, STnarrow and STwide were determined to be -0.17 K-1 and -0.06 K-1 , respectively, for tert-butyl alcohol in salol. Consequently, δ(ST)narrow/STnarrow = 190% and δ(ST)wide/STwide = 40% were obtained. Thus, the error δ(ST)/ST decreased from 190% to 40% when the interference fringe shifts were measured in the wide area in 0.25 mm intervals rather than in the narrow observation field.
In order to clarify the influences of atomic oxygen (AO) or the interaction between ultraviolet rays (UV) and AO to optical properties of silicone contaminants, UV- and AO-irradiated silicone contaminants were evaluated through optical property measurement. RTV-S691, a silicone adhesive with low volatiles content and minimum outgassing behavior for space utilizations, was used as an outgassing source, and two optical materials (magnesium fluoride and zinc selenide) were used for collecting contaminants from the RTV-S691. Optical properties were examined by Fourier transform infrared spectroscopy and Ultraviolet-visible-near infrared spectroscopy. RTV-S691 was heated to 125°C, while the two optical materials used for collecting contaminants were maintained at 25°C. The results show that UV- and AO-irradiation have impacted the optical properties of silicone contaminants, for example, some optical spectral peaks were disappeared by AO irradiation.