Modelling approaches for space weather studies in preparation for a Mars mission

Radiation is one of the most important risks to deep space exploration programs such as manned missions to the Moon and Mars. In preparation for such programs, it requires a thorough understanding of interplanetary space weather conditions and a timely forecast of their potential effects as a baseline for the development of mitigation strategies. Radiation damage in space comes mainly from two sources, Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs). The GCR is omnipresent, ubiquitous, and increases the chance of long-term health consequences. Their fluxes are modulated by the solar cycle evolution, shown as an anti-correlation between solar activities and measured GCR fluxes. A precise quantification of this modulation under different shielding environment (e.g., within a spacecraft in deep space or on planetary (sub-)surfaces) using both measurements and particle-transport models is essential for understanding and predicting the GCR-induced radiation and its changes through solar cycles. On the other hand, intense SEP events could result in very high doses in a short time period that may exceed the threshold to induce deterministic radiation effects and to result in severe damages to humans and equipment leading to the failure of the entire mission. Such events, despite of being rather infrequent and sporadic, are however very difficult to forecast and remain as a major challenge for space weather studies in preparation for deep space missions such as a manned Mars mission. Specifically speaking, the SEP radiation reaching an astronaut during a Mars mission (within a spacecraft in deep space or on the surface of Mars) may be completely different from of that detected near/on Earth, including the SEP onset time, spectra evolution, radiation intensity etc. This is due to (1) the different magnetic connection and distance of Mars (or the cruise spacecraft) from the acceleration and release region of SEPs near the Sun, and (2) the different in-situ shielding environment which modifies the energy and composition of the particles due to the interactions of primary particles with the shielding material and the generation of secondaries. The synergistic analysis and modeling of these two processes are particularly important to understand and eventually forecast SEPs and their radiation effects on Mars or inside the cruise spacecraft in preparation for mitigating their potential hazardous effects. In this talk, we will present some state-of-art and measurement-constrained modelling approaches for space weather studies which may serve as a baseline for the development of mitigation strategies to reduce potential hazardous radiation effects for a Mars mission.