国際宇宙ステーション「きぼう」から月面有人探査まで 一宇宙放射線に関する技術開発と基盤研究について一

抄録

Life science and material science experiments are being conducted in the International Space Station (ISS), which flies at a low earth orbit (LEO) of 300 to 500km above Earth. One of the objectives of the life science experiments in LEO are to estimate risks on crew members in long-duration space flights and to investigate quantitatively biological effects in a space radiation environment under microgravity. The space radiation fields in LEO have a broad distribution in linear energy transfer (LET). Therefore, measurements of absorbed doses only in space radiation fields are insufficient for investigating the biological effects and for assessing the risk of radiation on astronauts. Dose equivalents (or gray equivalents) considering LET distributions of the high LET particles and their high radiation quality factors (or relative biological effectiveness) must be measured for space radiation dosimetry. We have started space radiation measurements since just after attachment of the Japanese Pressurized Module `KIBO' to the ISS. A set of passive radiation detectors (a so-called `PADLES') to measure dose equivalents as well as absorbed doses in the KIBO pressurized module has been set up and swapped every 6 months or each expedition. We also have a strategy for investigating the influence of space radiation upon human lunar activity after ISS operation. The strategy consists of measurements of lunar radiation environments, research of biological effectsvon the moon, and administration for radiation protection of astronauts. In this report, we summarize the necessity of space radiation measurements on board the ISS and the feasibility study for future human space flights to the moon.