Effective radiation reduction in Space Station and missions beyond the magnetosphere

Results are presented from a a parametric study of the shielding effectiveness of low and high atomic number shields on biological dose equivalent for low-earth-orbit and interplanetary manned missions. It was found that the composition of shield materials has a major effect on the attenuation of radiation environments. For protons and galactic cosmic rays, the ordering of shield materials has a negligible effect. For electrons and secondary bremsstrahlung, both the order and composition are important parameters. The lowest atomic number materials are the most effective shield materials for protons and galactic cosmic rays. Low atomic number shields are also most effective in decreasing bremsstrahlung production. High atomic number shields are least effective for attenuation of protons and galactic cosmic rays, but are the best attenuators of both primary electrons (if the dose is dominated by primary electrons) and secondary bremsstrahlung (after production).