How Galactic Cosmic Ray models affect the estimation of radiation exposure in space

The radiation environment in space is a major concern for human spaceflight because of the adverse effects of high levels of radiation on astronauts’ health. Therefore, it is essential to perform radiation risk assessments already during the concept studies of a manned mission. Galactic Cosmic Rays (GCR) have been identified to be one of the primary sources of radiation exposure in space.This work presents an evaluation of the radiation exposure caused by GCR between 1970 and 2011 in near-Earth interplanetary space and at the orbit of the International Space Station (ISS) by making numerical simulations with the Monte–Carlo framework GEANT4. Commonly used GCR models – CREME96, CREME2009 and Badhwar–O’Neill2010 are used to describe the GCR spectra and the differences arising from the application of these different models in terms of absorbed dose and dose equivalent rates are investigated. Additionally, the depth distribution of the dose quantities and the relative contribution of particles with different energies to the total exposure during solar maximum and minimum conditions are studied.The differences in the spectra, described by the models, result in considerable differences in the estimation of the radiation exposure.

► Estimation of Galactic Cosmic Ray (GCR) exposure in space between 1970 and 2011. ► Investigation of the dependency of dose rates on depth and primary particle energy. ► Differences in dose rates using Badhwar–O’Neill’10, CREME96 & CREME2009 GCR models. ► No unusual rise in dose estimates for recent solar minimum period (2009–2010). ► Underestimation of dose for 2009–2010 as models do not describe elevated GCR fluxes.