S-520 Sounding Rocket Experiments of Materials Science under Microgravity

Sounding rockets are suitable platforms to provide the opportunity to carry out research in materials science, fundamental science, and biology. However, no sounding rocket developed in Japan has been served for microgravity experiments after termination of TR-1A rocket launching, while TEXUS and MAXUS rockets are frequently used as platforms for microgravity research in Europe. The present paper briefly describes the following in situ observation experiments under microgravity during free-fall flights of ISAS sounding rockets S-520-24 and S-520-28: (1) faceted cellular array growth, (2) diamond synthesis, (3) nucleation of WO3 and Fe in gas phase, and (4) nucleation of calcium carbonate. All the experiments were successfully performed in the 7 min microgravity conditions as a result of active control of spin of payloads. In the crystal growth experiments, heat and mass transport process near the crystals were optically visualized and then the kinetics on the growing crystal surface was quantitatively evaluated. In the nucleation experiments, nucleation rate under microgravity was drastically decreased compared with that under the terrestrial condition.