THE EFFECTS OF ORBITAL ALTITUDE AND INCLINATION ON SOLAR PARTICLE EVENT DOSES IN LEO

摘要

Doses in critical body organs of human crews in low-Earth orbit from energetic solar particle events can vary widely with the size and duration of the event, the location of the spacecraft in the Earth's magnetic field, the condition of the magnetic field and the radiation shielding available in the spacecraft. Previous work in this area investigated the sensitivities of calculated doses to the skin, ocular lens of the eye and bone marrow, for crewmembers in LEO, to variations in solar energetic particle event fluence levels and spectral hardness, spacecraft orbital inclination, geomagnetic field storm levels, and spacecraft shielding thickness for missions in a 400 km orbit. In general it was found that doses increase for higher inclination orbits, for higher storm indices, and for harder SPE spectra. The predicted doses, however, sometimes change dramatically for even small variations in the assumed conditions. In this work the study is generalized to orbital altitudes, 300 km - 600 km, to investigate the variations in crew organ doses from large solar energetic particle events resulting from variations in spacecraft altitude. Overall, it is found that doses from these events, for a particular orbital inclination, do not increase significantly with increasing orbital altitude.