Radiation Environments for Deep-Space Missions and Exposure Estimates

Abstract

Humans and onboard space systems (electronics, materials, payloads and experiments) are exposed to the deleterious effects of the harsh space radiations found in the space environment. The purpose of this paper is to present the space radiation environment extended to deep space based on space radiation environment models for the moon, Mars, Jupiter, and Saturn. The space radiation environment consists of high-energy protons and electrons that are magnetically “trapped” around planetary bodies that have an intrinsic magnetic field; this is the case for Jupiter and Saturn (the moon and Mars do not have a magnetic field per se). Trapped proton and electron models have been developed for Jupiter (GIRE model) and for Saturn (SATRAD model). The space radiation environment also consists of extremely energetic stripped elemental nuclei ranging from hydrogen (proton) to uranium, called the galactic cosmic rad iation (GCR) environment. In addition to trapped and GCR particles, the space environment is sometimes dominated by the emission of high-energy solar protons; these sporadic occurrences or events are called solar proton events (SPEs). Pa rticle spectra (flux vs. energy) and depth dose data are presented for the moon, Mars, Jupiter, and Saturn. The implications for human missions to the moon and Mars and robotic missions including “landers,” to Jupiter and Saturn are disc ussed in detail.