As microgravity experiments using the drop shaft, Japan Space Forum has offered the microgravity experiments opportunity since 1997 in the management of ``Announcement of Ground Research for Space Ulilization'' contracted to the National Space Development Agency of Japan. As the feature of microgravity experiments using drop shaft ◯High-quality and stable microgravity environment below 10－5 G can be achieved. (For about 4.5-10 seconds) ◯Experiments conditions can be changed easily. ◯Repeated experiments are possible about for 20 times a theme. For planning the experiment using drop shaft, different planning from other facilities is required. The experiment to make the most use of the advantage peculiar to this facility is also required. Moreover, when harnessing these features in the maximum, we ask the investigators following consideration: (a) Safety The safety check of the experiment equipment and samples carried into the capsule. (b) Intensity of experiment equipment The intensity check of the experiment equipment that bears the too heavy gravity acceleration generated in the braking zone. Now, the ground-based research activities on space utilization, ``2001 Research Solicitation for Research Themes of Utilization of International Space Station in the Fields of Life Science and Space Medicine'' are also performed. The importance of the microgravity experiment using the aircraft and the drop shaft facility has increased as a preliminary experiment. We expect the research theme through the ground-based research activities will advance to the theme using ``kibo'', and the interest of investigators towards space utilization will increase in future.

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Micro-Gravity Laboratory of Japan (MGLAB) which was established as a semi public corporation invested by the Prefecture of Gifu, City of Toki and private corporations, provides the micro gravity drop experiments inexpensively and repeatedly for researchers. Many researchers have carried out about 4,000 drop experiments by using MGLAB's facility since 1995. MGLAB's facilities are composed of a vacuum tube and drop capsule. The vacuum tube has 100 m free drop zone and 50 m braking zone. The drop capsule has about 0.3 m3 payload space and can load up to 400 kg experiment equipments. This facility can provide a stable 4.5-second micro gravity duration, and accuracy of micro gravity is 10－5 G. People who utilize MGLAB's facilities need to adjust the configurations of experiment equipments to MGLAB's interface specifications, which are mechanical combinations, power supplies, I/O signals and so on. The following outlines the micro gravity drop experiment facility, interface between the facility and the experiment equipments and experiment methods.

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The drop-shaft type microgravity experiment system of Japan Microgravity Center (JAMIC) in Kamisunagawamachi, Hokkaidou, is the largeset on ein the world boasting of a duration of 10 seconds of microgravity condition, and now in constant and effective use by many researchers and scientists from all over the world.

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Microgravity experiments of fluid dynamics have been carried out at the Japanese and German drop experiment facilities. Through my experiences of drop experiments, the system of drop facility at ZARM University of Bremen in Germany and the episodes of drop experiments are introduced. Some points to which we should pay attention for drop experiments, such as electrical noise, sequence table, and diffusion time, are also described.

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This paper describes gas-liquid separation and bubble removal technology using capillary, electrostatics and centrifugal force under micro-gravity condition. The authors discussed fluid behaviors in vane type surface tension tank experimentally and analytically, which has the function to separate liquid and gas using a surface tension. In addition to this, we investigated bubble movements by dielectrophoretic and centrifugal force in order to develop the bubble rejection device for microgravity condition. It was shown that these techniques are feasible to fluid management under microgravity condition. Also we refer to some know how required to build the experimental device and to prepare and conduct microgravity experiments using drop shaft facility.

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This article presents an overview of the utilization of drop tower facilities for liquid-fuel combustion studies. We present examples of experiments on the combustion of cylindrical liquid-fuel samples, interacting combustion of droplet pairs and the control of droplet combustion by acoustic disturbances. The existing drop towers are classified into three basic types. These drop towers are then compared using the results of the different combustion experiments. This article is intended to be a general introduction to drop tower experiments for a scientist.

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Role of microgravity experiment with drop facilities in combustion research field is discussed based on the experiences of drop experiments at MGLAB (Micro-Gravity Laboratory of Japan) and JAMIC (Japan Microgravity Center). Three important roles, that is, (1) the role as a dark background to investigate an elementary transport process in combustion phenomenon, (2) preliminary test field for space flight experiments, (3) environment to find out unexpected phenomena, are emphasized. Finally, the advantages of two large drop facilities,MGLAB and JAMIC, are individually described from the view of microgravity combustion research.

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In-situ measurement techniques are reviewed on the heterogeneous reactions including a crystal growth from solution, an electrochemical reaction on electrode and a boiling phenomenon at a heated surface. These reactions are traditionally utilized in the industrial separation technology and extractive metallurgy. The frontier of electrochemical reaction engineering has also been exploited in microelectronics and energy science fields based on the measurements. Some techniques can be applicable to the drop shaft facility. The characteristics inherent to the in-situ measurement techniques are described not only on the design of a quasi-two dimensional cell, but also on the optical deflection effect in a steep refractive index gradient. Some researches performed in a drop shaft are described. Boiling phenomena were observed with two-wavelength Mach-Zehnder interferometer. Malangoni convection caused by the non-uniformity concentration distribution appeared at the later stage of boiling of non-azeotropic mixture. The wettability of electrolyte introduced the different behavior of gas evolving electrodes, when the water electrolysis was conducted. Anodic dissolution phenomena were also observed with a common path interferometer. The numerical simulation results agreed with the observed transient behavior of interference fringe pattern. The careful and persevering preparations may provide the possibilities of new phenomena inside the drop shaft capsule, if in-situ measurement techniques are reasonably designed.

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A diamond is considered as a bright prospect material for semiconductors because of its wide band gap, high electron and positive-ion mobility and negative electron affinity. Many researches on the syntheses of diamond thin film have been performed, which utilize plasma chemical vapor deposition (CVD) method. But the detail mechanism of the synthesis of diamond have not been clarified yet, because the natural convection causes the disturbance to understand the phenomena related to the CVD processing under normal gravity. A diagnostic study of hydrogen-methane plasma was applied to the CVD experiments utilizing the 4.5 s drop shaft at Toki in Gifu and 10.0 s drop shaft facility at Kamisunagawa in Hokkaido. The plasma temperature was estimated based on the two-line radiance ratio method as a function of the position from anode. We also examined the delay time, which is taken to generate discharge plasma after adding high-voltage between electrodes. Moreover the pattern formation of the positive column and low-frequency fluctuation of plasma (0～50 Hz) that has been hardly focused on in the past study on plasma was examined.We found that (a) remarkable differences of the electron temperature of plasma were confirmed between the microgravity and the normal-gravity conditions, (b) the gravity affected the delay time, (c) the low-frequency fluctuation of plasma was affected by gravity level, and (d) the pattern formation dynamics of plasma emission on the anode was sensitive to gravity level.

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A new oscillating drop method was introduced to measure the surface tension, density and viscosity of a liquid without any external forces under microgravity. The optimization of the levitation method of a droplet is discussed. Since the accuracy of the values obtained by an oscillating drop method under microgravity is much higher than those from the previous methods, the method should be used to measure the thermophysical properties of several standard materials. The drop-shaft facilities, which produces a high quality microgravity condition, are required for this method.

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We recently reported our findings in regard to the physiological function that modulates cell mutability under 1 G conditions, and in this study we investigated the mutation-modulating activity in human and cultured cells after gravity-changing conditions produced by parabolic flight or by free-fall. The mutation-modulating activity was detected in serum from volunteers who underwent parabolic flight. Cultured human cells also showed the modulation-associated alteration, such as the induction of protease activity and gene expression, when they were exposed to gravity-changing stress produced by parabolic flight and by free fall. Thus, we hypothesized that the mutation-modulating function may proceed as follows; when humans are exposed to gravity-changing stress, serum factors are first released into blood, proteases in cells are activated by the factors, expression levels of genes are altered, and finally cellular mutability is regulated.

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We have carried out many experiments using an airplane and a drop tower to study the behavior of fish (medaka; Oryzias latipes) under microgravity. The methods and apparatus used in these microgravity experiments are introduced, with the detailed description of the setup and experimental procedures. An example of the fish behavior during a parabolic flight and its analysis are also shown.

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Unique in situ observations using an aircraft or a drop facility have been developed in Japan for the crystallization experiments under microgravity. This is because of the limited facilities in Japan for longer duration of microgravity experiments. Interferometry and phase sensitive microscopy have widely been employed for the crystal growth experiments not only from aqueous solution phases but also from melt or gases at elevated temperature as high as 1900°C . Microgravity was found to reduce the nucleation rate of crystals considerably, because of much less heterogeneous nucleation. Cosmic materials from melt have been synthesized under microgravity for the first time. Natural textures and chemical variations of cosmic materials have successfully been synthesized when microgravity or levitation method has been adopted. This is due to the very large supercooling obtained only when no crucible or holders for the melt or the solution has been used. In order to employ the interferometry more effciently in extreme conditions, a super-miniaturized interferometer (12Φ) has been developed.

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Fluidized bed has been widely used in many processes of petroleum, chemical and electric-power industries. In the bed, solid particles are fluidized by the flow of gas or/and liquid. The flow patterns in the bed are strongly affected by gravity-levels against drag forces. Minimum velocity for fluidization is one of the basic hydrodynamic characteristics of the bed. The behavior of a fluidized bed under various gravity-levels was observed using our high-gravity generator (1～10 g0). The effect of gravity-level on minimum fluidization velocity of a two-dimensional gas-solid fluidized bed was investigated. The experimental results were compared with previous works under normal gravity-level. For some kinds of particles categorized in group-A of the Geldart map under normal gravity-level, the values of minimum fluidization velocity approached those of minimum bubbling fluidization velocity as gravity level was higher. The experimental data of minimum fluidization velocity versus gravity-level (4.8＜Ar＜875) was in good agreement with the correlations which have been proposed for the data under normal gravity-level.

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Observation was made of the generation of liquid plugs in an inclined circular pipe subjected to a sudden change in the gravity level. The drop shaft of the Japan Microgravity Center ( JAMIC) was used to realize the gravity level change from the normal gravity to microgravity. The liquid plugs were first generated near the bottom of the pipe and subsequently generated toward the top of the pipe. The center and film thickness of the liquid plug and the transient time for the generation of the liquid plug were determined. Empirical relations were derived for these quantities.

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With an aim to clarify the effect of microgravity on protein crystal growth, we carried out terrestrial experiments by comparing the quality of the crystals grown in different supersaturation. In order to verify the generally believed hypothesis that the low concentration zone around the growing crystal has a positive effect on crystal growth in microgravity, systematic study on the correlation between supersaturation and protein crystal quality was carried out employing X-ray diffraction analysis with synchrotron radiation (SR). It was concluded that crystals grown in lower supersaturation have better diffractions with not only higher signal-to-noise ratio but also with better agreement between symmetry-related reflections.

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A microgravity experiment is described that takes into account not only physically critical conditions but also critical aspects from the managerial viewpoint, which include the experimental design, facility design, justification and public relations. What I learned from European scientists when I first started doing experiments on microgravity science will also be discussed.

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The know-how and lessons which we learnt through development of the High Temperature Furnace Type-II (HTF- II-6) are described. We also show problems to be solved for development of experimental facility in future and perspectives.

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A newly founded innovative educational institution; International Space University ISU, envisions enhanced capability of people working in the space sector in terms of professionalism and personal magnetism. This article indroduces the brief history of ISU, ISU's credo and objectives, statistical data of students, the programs offered by ISU. ISU curriculum pursues 3Is; International, Intercultural and Interdisciplinary and covers all the subjects relevant to space activities; engineering, physics,chemistry, biology, medicien, business/contract/marketing, law and regulations etc. The programs of ISU consist of 2 months Summer Session Program; SSP, 11 months Master of Space Studies; MSS, short term Professional Development Program; PDP, Annual Symposium, and search/Contract works.

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In order to study crystal growth mechanisms, NASDA has been preparing three crystal growth experiments in collaboration with principal investigators (PIs) and hardware engineers. The experiments will be carried out with the Solution Crystallization Observation Facility developed by NASDA for SPACEHAB (HAB-SCOF). HAB-SCOF has two in-situ measurement devices, a Mach-Zehnder-type two-wavelength microscopic interferometer and an amplitude modulation microscope. By using these devices, temperature and concentration distributions as well as growth rates will be obtained. For one experiment, an additional interferometer will be added into a cartridge to provide a more accurate temperature distribution. The obtained data will be used to verify theories, proposed by PIs, and to improve them if necessary

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Experimental topics for protein crystallization in micro-gravity environments are reviewed. There are increasing needs for higher quality protein crystals to design new drugs based on the 3D structure of disease related protein. Microgravity environments are suitable for the protein crystallization. Brief summary for the mechanism of micro-gravity effects including resent theory and speculation is described. In addition, policies for the determination of experimental conditions are summarized.

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