Long term variations of galactic cosmic radiation on board the International Space Station, on the Moon and on the surface of Mars

Abstract

The radiation environment in free space and the related radiation exposure is seen as one of the main health detriments for future long-duration human exploration missions beyond Low Earth Orbit (LEO). The steady flux of energetic particles in the galactic cosmic radiation (GCR) produces a low dose-rate radiation exposure, which is heavily influenced by several factors including the solar cycle, the presence of an atmosphere, relevant magnetic fields (as on Earth) and of course by the relevant spacecraft shielding. Investigations of the GCR variations over the course of a solar cycle provide valuable data for exploration mission planning and for the determination of the radiation load received due to the GCR environment. Within the current work these investigations have been performed applying three datasets generated on board the International Space Station (ISS) with the DOSTEL instruments in the frame of the DOSIS and DOSIS-3D projects, with the CRaTER instrument in a Moon orbit and with the MSL-RAD instrument on the way to and on the surface of Mars. To derive GCR dose contributions on board the ISS two procedures have been developed separating the contributions from GCR from passing’s through the South Atlantic Anomaly (SAA), as well as ways to extrapolate the GCR dose measured on board the ISS to free space based on various ranges of the McIlwain L-shell parameter. At the end we provide a dataset spanning the timeframe for GCR measurements on the ISS (2009 – 2011 & 2012 – 2019), Moon (2009 – 2019) and Mars (2012 – 2019), thereby covering the time span from the deep minimum of solar cycle 23, the ascending phase and maximum of solar cycle 24, and the descending phase of cycle 24, which is ongoing at the time of this writing.