5. ACKNOWLEDGMENTS

We would like to thank Prof. M. Kohno of Research Division for Space Propulsion, ISAS, for his support of constructing the gun facility and target sand used in the present experiment. We greatly acknowledge technical assistance from Mr. S. Yasuda, Mr. S. Sato, and Mr. S. Hirayama of En-gineering Support Department of ISAS, and Mr. K. Kobayashi and Mr. Y. Uchida of Space Operations Department of ISAS. Without their generous assistance in various aspects of the experiments, the present experiment could not have been completed.