Astronaut EVA exposure estimates from CAD model spacesuit geometry

Area of Science:

• Space radiation dosimetry
• Astronaut radiation exposure
• Extravehicular activity (EVA) safety

Background:

• International Space Station (ISS) assembly and maintenance demand more spacewalks (extravehicular activities, EVAs) than previous missions.
• Accurate assessment of radiation exposure during EVAs is crucial for minimizing astronaut risks and establishing safety limits.

Purpose of the Study:

• To determine and analyze astronaut radiation exposure during EVAs.
• To utilize detailed models of spacesuits and human anatomy for accurate dose evaluation.
• To establish radiation exposure limits for astronauts undertaking EVAs.

Main Methods:

• A detailed CAD model of the U.S. Space Shuttle EVA Spacesuit was used to represent astronaut directional shielding.
• NASA Computerized Anatomical Male and Female (CAM and CAF) models were employed for internal body dose assessment.
• The NASA LaRC HZETRN code (hadrons) and ELTRN code (electrons) were used for particle transport calculations through suit materials and body tissue, using AP8/AE8 environmental models.

Main Results:

• Calculated doses within CAM and CAF models from energy deposition along directional rays.
• Evaluated doses at multiple points on the skin and within the body.
• Included contributions from primary particles (protons, light ions, electrons) and secondary particles (brehmsstrahlung, target fragments).

Conclusions:

• Directional dose patterns were visualized using color relative intensity on spherical surfaces.
• The methodology provides a framework for assessing and managing astronaut radiation exposure during EVAs.
• This research supports the establishment of critical radiation exposure limits for long-duration space missions.