Simulating Space Radiation for Testing Shielding Material Effectiveness


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The space radiation environment poses health risks to astronauts. There are three sources of space radiation: trapped radiation, Solar Particle Events, and Galactic Cosmic Rays (GCR) and these sources consist primarily of protons and heavier (HZE) ions. NASA has developed a radiation protection strategy to limit risks that includes the use of countermeasures such as shielding. A correct risk assessment relies on an accurate evaluation of the shielding effects of spacecraft structures on the incoming space radiation environment. Since the complicated shielding geometry plays an important role, existing transport codes must be improved to predict dose deposition inside the vehicle. Computer simulations of spacecraft are often used to show the reduction in equivalent dose provided by spacecraft structures. However, published research has shown that increasing shielding does not always result in a reduction in equivalent dose. When interacting with spacecraft structure and shielding materials, high energy protons and HZE ions can produce secondary particles that can cause greater biological damage than the incident particle. Shielding optimization, therefore, requires an understanding of the contribution of the physical interactions to the dose and dose equivalent. Through the use of accelerator measurements and Monte Carlo simulations, the shielding properties were investigated for current and proposed spacecraft hull materials irradiated with protons and 56Fe ions at 1 GeV/n. Small differences were seen between materials; however, these differences could be important when performing the design trades necessary for long duration space mission planning. This improved understanding can be incorporated into the radiation protection in future spacecraft designs.



Space radiation, shielding, NASA