The natural ionizing radiation environment present in space poses risks to human exploration
that require mitigation. Space ionizing radiation consists primarily of highly energetic charged
particles including protons and heavy ions. Solar energetic particles (SEP) originate from
the Sun and are emitted during transient events referred to as Solar Particle Events (SPEs).
Galactic Cosmic Rays (GCR) originate outside the solar system and form a slowly varying background modulated by the solar cycle. Spacecraft designed for Exploration beyond Earth orbit
(BEO) do not benefit from the Earth’s magnetosphere protection and are subject to stricter
radiation design requirements than their low Earth orbit (LEO) counterparts. Spacecraft flying
beyond Earth orbit may also be exposed to the Van Allen (trapped radiation) belts environment depending upon their trajectories. Orion is NASA’s next generation crewed spacecraft,
developed specifically for Exploration missions. [...
