Updated deterministic radiation transport for future deep space missions.

Area of Science:

• Space radiation physics
• Computational astrophysics
• Astroparticle physics

Background:

• NASA's HZETRN and 3DHZETRN codes model space radiation for astronaut safety.
• Accurate radiation environment data is crucial for planning lunar and Mars missions.
• Existing models require updates for improved accuracy and validation.

Purpose of the Study:

• To present significant updates to deterministic radiation transport models.
• To couple charged muons and pions into existing transport solutions.
• To validate updated models against Geant4 and International Space Station (ISS) data.

Main Methods:

• Fully coupled charged muon and pion transport, including 3D pion production and interactions.
• Incorporation of low-energy proton recoils and charged pion capture/decay processes.
• Coupling of Geant4 cross-sections into HZETRN and 3DHZETRN for direct methodology comparison.

Main Results:

• Deterministic and Monte Carlo transport methodologies show excellent agreement when using identical nuclear cross-sections.
• Updated 3D procedures in 3DHZETRN are within 5% measurement uncertainty compared to ISS data at cutoff rigidities below 1 GV.
• The enhanced models accurately characterize the space radiation environment.

Conclusions:

• The updated deterministic codes provide a more accurate representation of the space radiation environment.
• These advancements are critical for ensuring astronaut health and mission success in deep space exploration.
• The validated models serve as fundamental input for space radiation risk assessments.