Astronaut Radiation Dose Calculation With a New Galactic Cosmic Ray Model and the AMS-02 Data

We present a new calculation of the astronaut dose rate from the galactic cosmic rays in free space at 1 AU. We use the unshielded isotropic fluence-to-dose conversion coefficients given in the International Commission on Radiological Protection publication 123. A new 3D and time-dependent solar modulation model based on Parker's transport equation as originally developed in Song et al. (2021, ) is used to calculate the galactic cosmic ray spectra at 1 AU. This model uses the recent local interstellar spectra of Corti et al. (2019, ), M. J. Boschini et al. (2020, , 2021a, ) to reproduce the PAMELA and AMS-02 observations between 2006 and 2019. The radiation dose calculated from our model and from the AMS-02 spectra in the same rigidity region agrees better than 1% for proton and helium in a time-dependent way, and at 2% level for six most contributing cosmic ray elements averaged over 7 or 8.5 years. The time-dependent dose rate analysis over 13 years shows an effective dose equivalent rate of 55-58 cSv/yr at solar minimum (January 2010) and 26 cSv/yr at solar maximum (February 2014).

Automated summary

We propose a new method to calculate the astronaut dose rate from galactic cosmic rays in free space at 1 AU. The calculation is based on unshielded isotropic fluence-to-dose conversion coefficients provided by the International Commission on Radiological Protection. A new 3D and time-dependent solar modulation model is used to calculate the galactic cosmic ray spectra at 1 AU. The model is validated against PAMELA and AMS-02 observations, and the calculated dose agrees well with AMS-02 spectra.