Modeling the Radiation Environment of Energetic Particles at Mars Orbit and a First Validation against TGO Measurements

Sending astronauts to Mars will be a milestone of future deep space exploration activities. However, energetic particle radiation in deep space and in the Mars environment is a major risk to the health of future human explorers. The nominal Martian surface radiation field contains primary Galactic Cosmic Ray (GCR) particles and secondary particles generated in the Martian atmosphere and the regolith. Some of these secondary particles may propagate upward and even be detected at the orbit of Mars contributing to the orbit radiation. Studying the Mars orbit radiation environment is critical for planning future Mars orbital missions. Therefore, we calculate the Martian orbit radiation dose rate considering the primary GCR spectra provided by the Badhwar-O'Neill 2014 model and the secondary particles modeled by the state-of-the-art Atmospheric Radiation Interaction Simulator. Specifically, we calculate the integral dose rate of each particle type and its dependence on orbit height, surface pressure, and solar modulation intensity. Our analysis shows that modulation intensity is the most dominating factor and that different surface pressures make less than a 1% impact. We also derive the sensitive energy range of detected particles contributing to the dose rate and further validate our prediction against the measured data by Liulin-MO on TGO at a circular orbit around Mars. This may conduce to predicting the radiation risks in Mars orbit and providing constructive reference parameters for the crewed space industry.