The Latest Jovian-Trapped Proton and Heavy Ion Models

Jupiter possesses the harshest trapped radiation environment in the solar system. Models of the Jovian-trapped radiation environment are a prerequisite for planning missions to this extreme environment. The high energy (>0.1 MeV for electrons and >1 MeV/nuc for protons and heavier ions) particle environment drives the shielding and microelectronic parts design for a spacecraft. Recently, models based on the measurements by the Galileo energetic particle detector and heavy ion counter have been updated for the trapped protons and heavy ions. The purpose of this paper is to describe these changes to the proton and heavy ion models and demonstrate their application to and relative impact on mission design. While trapped electrons at Jupiter dominate for total ionizing dose and displacement damage dose for typically shielded parts/materials (e.g., with ~100 mil or 2.54 mm of aluminum shielding), trapped protons can be a significant contributor to lightly shielded components (e.g., solar cells under 10-20 mil of cover glass). In contrast, although they will be described here for completeness, the Jovian-trapped heavy ions are typically not a driving environmental consideration for single event effects evaluations (their energies are so low that a small amount of shielding will attenuate the fluxes to levels below the interplanetary solar energetic particle and galactic cosmic rays).