The Real-time Radiation Monitoring Device (RRMD) is the only dosimeter that can give dose equivalent by direct measurement of LET distributions for space radiation. RRMD-III has the capability to measure LET of particles with wide range (0.2 ~ 600 keV/μm). The system and the dosimetric data on Space Shuttle Missions obtained by RRMD-III are summarized. And results of the comparison with the other dosimeters such as Tissue Equivalent Proportional Counter (TEPC) and DOSimetry TELescope (DOSTEL) are given.
