Shielding effectiveness depends on how many nuclei a particle has to collide with per unit mass — light, hydrogen-rich materials outperform heavy metal shielding pound for pound.
dose ~ flux * energy * (1 - attenuation)
attenuation ~ layers * effectiveness
- Incoming particle flux — cosmic-ray and solar-storm particle rate striking the hull.
- Shield layers — number of shielding layers built into the hull design.
- Particle energy spectrum — mix of particle energies, from routine GCR flux to a rare solar-storm spike.
- Shield material effectiveness — how well the chosen material (polyethylene beats aluminium per kg) stops particles.
Hydrogen-rich materials like polyethylene shield better per kilogram than metal, which is why modern spacecraft designs favour it over the aluminium hulls of early missions.