As one of the space biology experiments for the second International Micro-gravity Laboratory ( IML- 2 ) mission scheduled in the summer of 1994, the project of 'Mating behavior of the fish, medaka '(Project name “MEDAKA”)has been selected. For the preliminary experiment, parabolic flights were carried out to observe the fish behavior under μG for five different inbred strains of medaka. There existed a clear strain-difference in the behavioral response of the fish under μG and light conditions: Some strains looped and other strains did not. However, under μG and dark conditions, all the fish of the five strains did loop. This indicates that fish use visual senses in controlling their posture under μG. In the laboratory, visual acuity is checked for each strain and also for F1generation between two strains, using a rotating striped-drum apparatus.
Homogeneous silica-aluminas were synthesized by hydrolysis of mixed alkoxides under short-time microgravity (μ - G) circumstance of 10-4G for 10 seconds using the microgravity experimental facility of Japan Microgravity Center (JAMIC, Kamisunagawa in Hokkaido).The hydrolysis of the mixed alkoxides was carried out by the mixing of benzene solution of methyltriethoxysilane and aluminum isopropoxide with water containing ammonia under μ -G circumstances to prepare the silica-alumina gels. The Silica-aluminas were synthesized by the heat treatment of the gels. The silica-aluminas synthesized under μ-G circumstances, had more homogeneously dispersive silica and alumina, finer particles, narrower particle size and higher catalytic activity than those synthesized under 1-G.
Variable reduced (from micro-to normal-)gravity level experiment was performed by a newly developed speed controlled drop-tower. The speed of falling frame, in which various low-gravity experimental apparatus are installed, is controlled by a servo-motor and computer. Falling height is about 12m and the duration time of the low gravity level is at least 1 sec. The g-jitter level is about 5 x10 -2 G .
The parabolic flight supplies microgravity environment in a cabin and assures of carrying out various microgravity experiments. The first parabolic flight in Japan was done in 1986 by Mitsubishi MU-300, small jet plane, and up to now 2000 parabolic flights have been carried out by MU-300 in total. In this paper, method and feature of parabolic flight by MU-300 are reported. Diamond Air Service Co. located near Nagoya airport offers parabolic flight and its support for a microgravity experiment. The parabolic flight by MU-300 provides microgravity periods of approximately 20 seconds with below 3x 10-2 G condition. 6 - 10 times of parabolic flight have been done per 1 flight depending on preparation time of each experiment. Various G conditions between 0.03G and 2.5G can be provided in excess of 20 seconds. Typically, two experimental themes are flown simultaneously, and one of those operators can be on board. NASDA developed support-equipment for MU-300 microgravity experiment such as electric power supply, data recorder, data logger and video system. These equipments are able to make remote-operation at system operator's seat.