Abstract
Solar Energetic Particles (SEP) are one of the major sources of the
martian radiation environment. It is important to understand the
SEP-induced martian radiation environment for future human habitats on
Mars. Due to the lack of global intrinsic magnetic field, SEPs can
directly propagate through and interact with its atmosphere before
reaching the surface and subsurface of Mars. Since Mars has many high
mountains and low-altitude craters where the atmospheric thickness can
be more than 10 times different from one another, the SEP-resulted
surface radiation level may be very different from one location to
another. We thus consider the influence of the atmospheric depths on the
martian radiation levels including the absorbed dose, dose equivalent,
and (human-)body effective dose induced by SEPs at varying heights above
and below the martian surface. The state-of-the-art Atmospheric
Radiation Interaction Simulator based on GEometry And Tracking
Monte-Carlo method (AtRIS/GEANT4) has been employed for simulating
particle interactions with the martian atmosphere and terrain. We find
that even the thinnest martian atmosphere reduces radiation dose from
that in deep space by at least 65\%, and the shielding
effect increases for denser atmosphere. Furthermore, we present a method
to quickly forecast the SEP-induced radiation in different regions of
Mars with different surface pressures.