This paper describes results of the thermal-hydraulic performance experiment of the two-phase flow loop using a sounding rocket which can maintain a gravity level of 10- 4 g0 for about six minutes. The feasibility study for this system had been conducted for loading into an experiment module of the sounding rocket. A flight model of the experiment system was designed and constructed in 1992. The experiment was successfully performed on September 17, 1993, and a thermal equilibrium of the flow loop could be obtained under microgravity. The flow pattern became the froth flow at the outlet of a cold plate, and isothermal condition in the cold plate was established by the two- phase flow operation. Details of the flow behavior, the heat transfer coefficient, and the pressure loss under microgravity are described.

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Real-time observation of the melting and solidification of the system PbBri-PbCh under microgravity was successfully performed using a sounding rocket. An analysis of the solid-liq­uid interface shape, liquid flow and growth stability provides basic data concerning crystal growth from a melt. he interface shape is convex towards the melt during melting and becomes almost flat upon solidification, which agrees well with the results of a computational thermal analysis. The liquid flow observed during melting had a velocity between 0.2 mm/ s and 1.5 mm/ s. This is much higher than expected and is most likely due to Marangoni convection. Although PbBr 2 melt is capable of wetting with the quartz, traces of microscopic free surface areas during solidification are observed on the grown crystal surface. The microscopic free surface is the origin of Marangoni convection. Observation of the Marangoni flow in the liquid wettable to an ampoule wall is the first time and is of much interest. The experimentally determined critical G/ R for stable growth is 3.3 K·h/ cm2, which agrees well with 2.7 K· h/ cm2 derived numerically using the physical properities of the PbBri-PbCh system.

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In the second International Microgravity Laboratory (IML-2) carried out in July of 1994, four of a small Japanese killifish (Medaka, Oryzias latipes) made a space flight of 15 days. These four Medaka fish performed their successful mating behavior in space for the first time among vertebrate animals. Moreover, the eggs laid developed normally till hatching fry (baby fish) in space. The success of this fish mating experiment totally depends on selection of the four fish sent to space. Using a strain of fish which do not loop under microgravity, further selection was carried out checking visual acuity and degree of dorsal-light reaction of each fish. This paper describes how the experiment was prepared and what were achieved in space.

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AstroNewt experiment was conducted on the Second International Microgravity Laboratory in 1994. During the mission, air bubble was developed in the cassette of Aquatic Animal Experiment Unit. In contrast to the flight equipment, air bubble was never formed in the equipment on ground. Pressure distribution in its water circulation loop and air pressure at gas exchange part might cause formation of bubble in the flight model.

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In a space experiment using Space shuttle/Spacelab (IML-2 mission), the adaptation of goldfish behavior during flight and re adaptation after landing were investigated. The behavior of 6 goldfish (1 normal, 1 with otoliths removed on both sides, 4 with otoliths removed on one side) were recorded with a video camera and analyzed. On the first day of the mission, the two fish with otolith removed on one side showed flexion of body towards the operated side. These fish also showed rolling behavior towards the operated side. However, the body flexion disappeared on the fifth day or eighth day. No rolling responses were ob­ served after that time. The normal fish and the fish with the otolith removed on both sides showed backward looping responses during the 13 day mission. However, the frequency of the looping decreased during the flight. These results suggest that the behavioral disfunction and the adaptational process in space are dependent on vestibular inputs.

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SFU was launched by the NASDA H-11 Rocket in March 1995 and reached a circular orbit of 486 km altitude. The observation of astronomical infrared light and space biology experiment with newts have been successfully completed so far. Science and technology experiments, industrial ex­periments using furnaces, and JEM (Japanese Experiment Module)-related experiments are under way. After the science mission, SFU ;illbe retrieved by the Space Shuttle orbiter (STS-72) in De­cember this year. This report describes how the flight operation is conducted to control SFU, including mission planning, control facilities and stations, control team organization, and operation proce­dure.

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