Galactic cosmic ray environment predictions for the NASA BioSentinel Mission, part 2:Post-mission validation

The BioSentinel CubeSat was deployed on the Artemis-I mission in November 2022 and has been continuously transmitting physical measurements of the space radiation environment since that time. Just before mission launch, we published computational model predictions of the galactic cosmic ray exposure expected inside BioSentinel for multiple locations and configurations. The predictions utilized models for the ambient galactic cosmic ray environment, radiation physics and transport, and BioSentinel geometry. Now that the nominal six-month BioSentinel mission has completed and some additional time has passed, those pre-launch predictions and additional model components can be validated. Dose-rate and linear energy transfer (LET) spectral measurements from the on-board dosimeter are presented along with a summary of the computational models used to calculate exposure quantities of interest. Sensitivity tests are performed to gauge the impact of various model choices on these quantities. Satellite data collected during the BioSentinel mission are used to provide some measure of independent validation for the galactic cosmic ray model used in the present calculations. It is shown that the combined models are in excellent agreement with the measured dose-rate. Model calculations agree well with measurement below ∼10 keV/µm and underpredict at higher LET. It is argued that the underprediction is likely due to detector response or low energy anomalous cosmic ray contributions able to reach the thinly shielded side of the on-board dosimeter.