Shielding from solar particle event exposures in deep space.

Area of Science:

• Space physics
• Astrobiology
• Radiation biology

Background:

• Astronauts in deep space are exposed to solar particle events (SPEs).
• Accurate assessment of radiation dose and biological effects is crucial for astronaut safety.
• Understanding the biophysical aspects of SPE exposure informs protection system design.

Purpose of the Study:

• To examine the physical composition and intensities of SPE exposures on sensitive astronaut tissues.
• To establish significant fluence levels and expected doses/dose rates from past SPE observations.
• To evaluate the effectiveness of polymer shielding compared to aluminum for spacecraft.

Main Methods:

• Utilized response functions to convert particle fluence into organ-averaged dose and dose equivalent.
• Employed the BRYNTRN transport code to simulate the local radiation environment for sensitive tissues.
• Assessed bioresponse models relevant to tactical nuclear warfare for space radiation applications.

Main Results:

• Determined significant fluence levels and expected doses/dose rates for major past SPEs.
• The BRYNTRN code provided detailed local environment data for sensitive tissues.
• Polymer shielding demonstrated a substantial safety factor compared to equal-mass aluminum shielding.

Conclusions:

• Clarified biophysical aspects of SPE exposure, aiding RBE and dose rate effect assessments.
• Polymer shielding offers superior protection without increasing spacecraft mass.
• Current polymer shielding designs provide adequate protection against even hypothetical, extreme SPEs.