Secondary proton buildup in space radiation shielding

Area of Science:

• Space science
• Radiation physics
• Materials science

Background:

• Prolonged exposure to space radiation is a major hazard for long-duration human space exploration.
• Relativistic protons are the most abundant ion species in galactic cosmic rays, necessitating effective radiation protection strategies for space crews.
• Designing spacecraft and habitats requires understanding the shielding effectiveness of various materials against space radiation.

Purpose of the Study:

• To compare the shielding effectiveness of standard and composite materials against relativistic protons.
• To assess the feasibility of current materials in mitigating radiation dose for future space missions.
• To validate simulation models against experimental data for radiation shielding design.

Main Methods:

• Experimental measurement of absorbed dose using Al2O3:C optically stimulated luminescence dosimeters.
• Shielding effectiveness evaluation using a 1 GeV proton beam at the NASA Space Radiation Laboratory.
• Comparison of experimental results with simulations using the FLUKA Monte Carlo radiation transport code.

Main Results:

• All tested shielding materials and depths (up to 30 g/cm2) failed to reduce absorbed dose below the level measured by the unshielded front detector.
• Absorbed dose measurements showed good agreement with FLUKA code simulations.
• The effectiveness of the shielding materials was limited against the high-energy proton beam.

Conclusions:

• Current shielding materials are insufficient to reduce absorbed dose to safe levels for long-duration space missions involving significant proton exposure.
• Further research into advanced shielding materials and strategies is crucial for astronaut safety.
• Accurate simulation tools like FLUKA are valuable for predicting radiation shielding performance.