Simulation of the GCR spectrum in the Mars curiosity rover's RAD detector using MCNP6

Area of Science:

• Planetary Science
• Space Radiation Physics
• Astrobiology

Background:

• Galactic cosmic rays (GCRs) pose a significant radiation hazard for human exploration of Mars.
• Understanding GCR propagation through the Martian atmosphere is crucial for mission planning and astronaut safety.

Purpose of the Study:

• To simulate GCR propagation through the Martian atmosphere to the surface using MCNP6.
• To compare simulation results with in-situ measurements from the Radiation Assessment Detector (RAD) on the Curiosity rover.
• To evaluate the accuracy of space radiation modeling in the context of Martian surface conditions.

Main Methods:

• Utilized MCNP6 Monte Carlo code for GCR transport simulations.
• Tracked ions Z=1 through Z=28 and secondary particles in 4π and 30° off-zenith acceptance angles.
• Compared simulated absorbed dose rates and dose equivalent rates with RAD measurements.

Main Results:

• MCNP6 4π absorbed dose rate simulation: 307.3 ± 1.3 µGy/day (RAD measured 233 µGy/day).
• MCNP6 4π dose equivalent rate simulation: 473.1 ± 2.4 µSv/day (RAD reported 710 µSv/day).
• Discrepancies observed between simulated and measured radiation levels.

Conclusions:

• Current MCNP6 simulations show differences compared to RAD measurements of surface radiation on Mars.
• Further investigation into GCR interactions within the Martian atmosphere and detector response is warranted.
• Refining space radiation models is essential for accurate risk assessment for future Mars missions.