Galactic cosmic radiation
From NewMarsWiki
Galactic cosmic radiation (GCR) particles are more difficult to shield against than those from SEP events. Because their energies are much higher than for particles resulting from SEP events, small uncertainties in dose projections can lead to a nearly exponential increase in the required shielding mass for a given level of acceptable risk to the crew of a manned mission to Mars.
The Martian Radiation Environment Experiment (MARIE) is measuring GCR levels during the transit to Mars and also at Mars.
