Microgravity experiments for ice crystal growth were conducted twice in the Japan Experiment Module “Kibo” of the International Space Station. Experimental cartridges newly developed for each experiment were transported to the space station and installed in the SCOF facility. All of the experiments were possibly could be performed by using a tele-control system on the ground. Crystal patterns during free growth of ice crystals in supercooled water were observed by using specially designed interference microscopes. Experiments were carried out for ice crystal growth in supercooled pure water (D2O) and in a supercooled solution (H2O) of antifreeze glycoprotein. Based on analysis of moving images, the pattern formation mechanism of ice dendrites in pure water and the fluctuation mechanism of growth rates in protein solution are discussed.
We and Olympus Engineering Co.，Ltd. developed laser confocal microscopy combined with differential interference
contrast microscopy (LCM-DIM), by which elementary steps (0.37 nm in thickness) on ice crystal surfaces can be visualized in situ at air-ice interfaces. Using LCM-DIM, we observed surface melting processes of ice crystals in situ, and found that an ice basal face grown from water vapor exhibits two types of quasi-liquid layer (QLL) phases that have different morphologies and dynamics. In this review, we show how these QLL phases emerge from an ice basal face. We found that round liquid-like drops (an α-QLL phase) emerge from outcrops of screw dislocations, and that thin liquid-like layers (a β-QLL phase) appear from crystal surfaces where many microdefects are embedded. These results strongly suggest that strain caused by lattice defects induces the appearance of both QLL phases. In addition, we also found that a β-QLL phase spontaneously forms at the interface between an α-QLL phase and a basal face when the diameter of an α-QLL phase
becomes larger than several 10 µm. This result implies that a β-QLL phase has an intermediate structure between those of an α-QLL phase and a basal face.
The microgravity experiment mission FACET (Investigation on Mechanism of Faceted Cellular Array Growth) was carried out under long duration microgravity on the International Space Station (ISS) in 2010. FACET aimed to clarify the mechanism of a faceted cellular array growth by precisely observing the phenomena at the solid/liquid interface. Phenyl salicylate / t- butyl alcohol alloy was used as a sample material instead of semiconductors or oxides. The crystal growth processes were visualized in situ using a microscope and an interferometer, especially focusing on changes in temperature and concentration in the sample. The temperature and concentration distributions in the melt during the growth were precisely measured with high spatial resolution. Negative temperature gradient as well as negative concentration gradient ahead of the S/L interface can be expected to be the driving forces of the morphological instability. It is evident that the conventional model based on the frozen temperature approximation is insufficient to explain the growth mechanism of the faceted cellular array
History of in-situ observation of crystal growth under microgravity has been reviewed emphasizing its importance for the analysis of crystal growth mechanisms under microgravity. Examples have been selected from our solution growth experiments with an intention to reveal why some crystal quality exhibited better quality in the perfection. Constrains to get better perfection have been discussed. Both morphological instability of the crystal surface and impurity incorporation play an important role to get better quality lysozyme crystals. Since important parameters to improve crystal quality have been clarified from the “in-situ” observation, these constrains will be given based on crystal growth mechanisms.
We focus on the growth mechanism of protein crystals and their perfection. The growth mechanism will be studied by surface observation and by measuring growth rates. Crystal defects will be studied by special etching and X-ray topography. We successfully carried out Nanostep experiments in 2012 using lysozyme crystals as model protein crystals. To generalize this result, a NanoStep2 experiment is planned to be flown in near future using glucose isomerase crystals. We need to obtain ground based data for the comparison with the Nanostep data. International collaboration is important to share a wide range of expertise for optimal scientific interpretation from different points of view.
We performed microgravity experiments of homogeneous nucleation of iron from the vapor phase using the sounding rocket S-520-28 on December 17, 2012. The purpose is determination of a sticking probability of iron during the nucleation from the supersaturated vapor, because the sticking probability is one of the most uncertain physical quantities to understand the formation process of cosmic dust based on nucleation theories. We prepared the specially designed MachZehnder-type interferometers with an evaporation chamber and camera recording systems to fit the space and weight limitations of the rocket. Three same systems, named DUST 1 to 3, were installed into the rocket. Iron was evaporated in an argon gas and then it was cooled and nucleated to form nanoparticles. The temperature and concentration of iron vapor at the nucleation site are determined from the movement of the interference fringe. Here, we present the brief summary of the experiments and the preliminary results of the homogeneous nucleation from iron vapor under microgravity.
There are still many students who are not familiar with science, especially physics. It might be because physics mostly use symbols and numbers, and is not easy to apply the knowledge into everyday lives. Also, the difficulty to observe the phenomenon itself can lead to aversion. Feeling that physics is difficult to understand can lead to discouragement, and therefore makes it more difficult to correct the misconceptions developed in daily lives, and this might take part in the vicious circle.
In order to overcome this problem, we have developed a Rube Goldberg machine that shows several phenomena in physics. By linking several experiments together, we assume that it will attract students’ interests, as well as be useful in physics class. Our goal is to record this machine under zero-gravity, and actually use it in physics class after the experiment, and test its effectiveness.
In recent years, the research on flexible space structure is rapidly advanced in many country. One of the examples of the flexible space structure, the authors has been developing a nano-satellite named “SPROUT“. The main mission of SPROUT is deployment demonstration of combined membrane structure by the inflatable tube. But, flexible space structure is difficult to experiment on the earth because air drag and gravity is very affected. So, we need know numerical analysis result of deployment dynamics. However, it is not enough data because the results of deployment demonstration on orbit are very few. So the purpose of this experiment, we establish the new estimation method of flexible space structure by ground experiment and microgravity experiment. We think the results of this experiment are big steps of realization of large scale of flexible space structure.
In this paper, the author introduces the results of experiment and the new estimation method of flexible space structure by ground experiment results.
In December 2013, the last parabolic flights for the Student Zero-Gravity Flight Experiment Contest in Japan were successfully conducted by JAXA with support of Japan Space Forum (JSF) and Diamond Air Service (DAS). In this paper, we describe the overview of the program and the parabolic flight experiment, and also the statistics and brief summary of all of the experimental themes conducted in the past 11 years.