We are preparing to return humans to the Moon and setting the stage for exploration to Mars and beyond. However, it is unclear if long missions outside of Low-Earth Orbit (LEO) can be accomplished with acceptable risk. The central objective of our project, the Earth-Moon-Mars Radiation Environment Module (EMMREM), is to develop and validate a numerical module for completely characterizing time-dependent radiation exposure in the Earth-Moon-Mars and Interplanetary space environments.

Space radiation hazards pose one of the most serious issues to future human and robotic exploration to the Moon and beyond:

• Galactic Cosmic Rays (GCRs) are an ever-present background radiation that originate from outside our solar system and produce chronic but not acute exposures. GCRs are extremely difficult to shield against. Astronauts under nominal shielding (e.g., a few gm/cm2 of aluminum) could accumulate a career limit due to GCRs in roughly 3 years. We need to understand the current constraints imposed by GCRs as a function of mission transit time, shielding materials and thickness, and develop better techniques to shield them.
• Large Solar Energetic Particle (SEP) events defined here to include ions (also referred to as Solar Particle Events, SPEs) are extremely dangerous to astronauts. To mitigate the hazard they pose, we must develop the ability to predict when and where they will occur, and we must provide adequate shielding against them.
• There are unique radiation environments at each planet or satellite. At Earth, we have thoroughly characterized locations of the radiation belts, which allows us to mitigate the hazard they pose by transiting them rapidly. For future human and robotic exploration of other planets and satellites, we must characterize the planetary radiation environments so that appropriate mitigation strategies and adequate shielding are designed.

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