Space radiation quality factor for Galactic Cosmic Rays and typical space mission scenarios using a microdosimetric...

Area of Science:

• Space science
• Radiation biology
• Astrobiology

Background:

• Space radiation, specifically Galactic Cosmic Rays (GCRs), presents a significant carcinogenic risk to astronauts.
• Radiation risk is determined by radiation quality, defined by energy deposition patterns at the DNA level.
• Quality factors, dependent on Linear Energy Transfer (LET) or lineal energy (y), quantify this risk for stochastic biological effects.

Purpose of the Study:

• To calculate the average lineal energy (y) of GCR for various space mission scenarios.
• To assess the carcinogenic risk to astronauts by evaluating radiation quality factors.
• To compare a modified microdosimetric Theory of Dual Radiation Action (TDRA) with existing models and experimental data.

Main Methods:

• Utilized NASA's OLTARIS platform to simulate GCR environments behind aluminum shielding (0-30 g/cm²).
• Calculated lineal energy spectra (y) in 1 μm liquid water spheres using a generalized analytical model.
• Employed a modified microdosimetric Theory of Dual Radiation Action (TDRA) for calculations.

Main Results:

• TDRA-based y-values for Low-Earth Orbit (LEO) and deep space missions showed differences up to 10% and 14% from ICRP-based values, respectively.
• TDRA-based y-values differed by up to 3% (LEO) and 6% (deep space) from NASA's y-model.
• Calculated y-values demonstrated good agreement with measurements from the International Space Station (ISS) and the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD).

Conclusions:

• The modified TDRA provides a reliable method for calculating GCR radiation quality factors for space missions.
• The findings support the use of microdosimetric approaches for accurate astronaut radiation risk assessment.
• This research contributes to understanding and mitigating the health risks associated with long-duration space exploration.