Speaker
Description
The interactions of galactic cosmic and solar energetic particle radiation with planetary atmospheres and surface regolith/bedrock may lead to significant modification to the local surface particle field due to the attenuation of the primary radiation and secondary particle production in the materials. This paper introduces a new Geant4-based tool, GRAPPA, that generates GDML geometries and other associated inputs needed to perform 3D calculations of Martian and Lunar radiation environments using ESA’s GRAS model. GRAPPA produces position-, seasonal- and local time-dependent geometry and magnetic field information based on:
- The European Mars Climate Database (MCD) v5.3 to define the Martian atmospheric composition and density as well as the surface precipitates.
- The SOLCOMPI database of Gonçalves et al is used to account for the surface soil composition of Mars. This database has been derived from gamma-ray spectrometer data collected by Mars Odyssey’s MGRS instrument. For the Moon, GRAPPA uses a similar surface composition dataset based on measurements from Lunar Prospector’s GRS instrument.
- Local magnetic field effects on low energy charged particles can be modelled using either the Cain et al or Purucker et al field models.
The input command set allows for easy control of the geometry, the dimensions of which can be for local (~10s metres) to planetary scales. For “local scale” GRAPPA surface geometries, recent changes to GRAS allow the user to easily overlay GDML-defined habitat geometries, mission equipment and anthropomorphic phantoms, thus allowing very detailed analyses of the local radiation environment on astronaut crews. This paper will include discussion of potential use-cases for the software and also briefly describe the GUI interface to GRAPPA provided through ESA's Human Interplanetary Exploration Radiation Risk Assessment System (HIERRAS).
