Abstract
The research efforts in radiation biology in space has recently been accumulated in Japan since the first space radiation biology experiments was conducted by Dr. Sohei Kondo in the early human space flight research at United States. In Japan, frequent opportunities for the space radiation experiments have been offered by NASDA (currently JAXA) after the participation to the first International Microgravity laboratory (IML-1) mission at 1992. A series of Spacelab missions, Spacelab-J, IML-2, Space Shuttle/Mir, were dedicated internationally for the multidisciplinary research. The space radiation biology experiments in early phase conducted in Japan employed stable specimen during the mission such as plant seeds, bacterial spores, and Altemia eggs to survey the biological effects during the space flights. In the later phase, more sophisticated experiments were planned and conducted using fruit fly, rat, plasmid DNA and its repair enzymes. It was also recognized the importance of the physical dosimetry inside the space vehicle at the lower Earth orbit to quantitize the radiation environment. During the early space radiation biology experiments, the plastic nuclear track detector such as CR-39 was only available to obtain the LET spectra of the composite particle radiation field. A real-time radiation monitoring device (RRMD) was simultaneously developed by NASDA and introduced to the space radiation biology experiments to obtain more precise LET spectra as well as spatial and tome resolutions. This report summarizes the recent efforts from the past radiation biology experiments in space.
