Space radiation analysis: radiation effects and particle interaction outside Earth Magnetosphere using GRAS and GEANT4

Abstract: Detailed analyses of galactic cosmic rays (GCR), solar proton events (SPE),
and solar fluence effects have been conducted using SPENVIS and CREME96 data
files for particle flux outside the Earth’s magnetosphere. The simulation
was conducted using GRAS, a European Space Agency (ESA) software based on
GEANT4. Dose, dose equivalent and equivalent dose have been calculated as
well as secondary particle effects and GCR energy spectrum.
The results are based on geometrical models created to represent the
International Space Station (ISS) structure and the TransHab structure. The
physics models used are included in GEANT4 and validation was conducted to
validate the data. The Bertini cascade model was used to simulate the
hadronic reactions as well as the GRAS standard electromagnetic
package to simulate the electromagnetic effects.
The calculated total dose effects, equivalent dose and dose equivalent
indicate the risk and effects that space radiation could have on the crew,
large amounts of radiation are expected to be obtained by the crew according
to the results. The shielding comparison between ISS and TransHab indicate
that a tradeoff between the two will have to be made, since the first has a
higher protective ratio compared to the TransHab: on the other hand
the second one is more flexible and could eventually become a larger
structure. The GCRs effects upon the structure are found to be comparable to
experimental data.