Radiation Environment and Effects Analysis of the Zodiac Pioneer Mission

ESA's Zodiac Pioneer mission targets Near-Earth Asteroids (NEAs) with potential rendezvous opportunities within the next 8 years, representing interesting targets for the Planetary Defense roadmap. The mission involves designing a small satellite platform capable of reaching various targets across different interplanetary trajectories, considering the asteroid 99942 Apophis as first case study given its close approach to Earth on April 13, 2029. Throughout the mission, the radiation environment will be highly mutable due to variations in solar activity and changes in the spacecraft's distance to both the Sun and Earth. These variations translate into different radiation sources affecting the spacecraft's onboard electronics. A comprehensive analysis requires characterizing each mission phase with the related radiation environment. However, conventional tools fail to do such an accurate analysis due to the unavailability of defining multi-segment interplanetary missions and adopting a minimum mission length of 6 months. To address this, we developed a new framework to estimate the total ionizing dose along the spacecraft's trajectory. The framework is built upon a dose dataset acquired from ESA’s SPENVIS tool, accounting for different mission durations, Sun distances, and solar activity. By evaluating trajectory-specific factors, our method accurately estimates radiation exposure, providing a more tailored and realistic assessment of the dose contribution than conventional tools that rely on worst-case scenarios. This approach avoids TID overestimation and highlights critical differences between potential mission trajectories under study, avoiding generalities.