Deep Space Radiation Hazards

Once outside the protection of Earth's magnetosphere, spacecraft and crews are exposed to a lethal radiation environment.

The Two Primary Threats

• Solar Proton Events (SPEs): Sudden bursts of intense radiation from solar flares. Highly lethal but localized in time. Can be mitigated with localized "storm shelter" shielding (e.g., water walls).
• Galactic Cosmic Rays (GCRs): Constant, isotropic high-energy background radiation. Extremely difficult to shield against, as secondary particle cascades (spallation) can make thick metal shielding worse than no shielding at all.

Plastics and water (hydrogen-rich materials) are the most effective shielding per unit mass against GCRs.