Space Station Radiation Dosimetry and Health Risk Assessment 932212

Current dosimetric practices do not provide comprehensive classification of high-energy charged particle radiation, so that the ability to adequately project health risk to astronaut crews is limited. To address this shortcoming in dosimetry for Space Station missions, a new generation of active radiation monitors is being developed to supplement traditional dosimetry. One active monitor is a Tissue Equivalent Proportional Counter (TEPC) to measure the linear energy transfer (LET) spectrum of space radiation. Two versions of a second type of active monitor, the Charged Particle Directional Spectrometer (CPDS), will be deployed, one internal and one external to the Station. The CPDS consists of a stack of lithium-drifted silicon detectors used to classify the radiation by particle charge and energy. The comprehensive data set obtained by using the TEPC and the CPDS permits significant improvement in assessing crew radiation exposures. LET spectral measurements made by the TEPC provide a direct measure of the biological equivalent skin dose to the crew, whereas the charge and energy spectral data measured by the CPDS are required inputs to anthropomorphic transport codes for estimation of organ-specific doses. The combined effects of comprehensive dosimetric measurements and improved radiation transport models will enhance NASA's capability to assess the impact of exposure to space radiation for both low Earth orbit and exploratory class missions.