A Reflection-Equivariant Mamdani Fuzzy System for Relative Total Ionising Dose and Solar-Proton Exposure Triage of Spacecraft Mission Scenarios

Spacecraft radiation assessment requires expert interpretation of continuous environment-model outputs. We present a reflection-equivariant Mamdani fuzzy system for relative triage of modelled total ionising dose (TID) and solar-proton exposure. Radiation environment severity and solar-proton severity are derived from OMERE 5.9.5 runs of the AE9/AP9 (IRENE 1.57.004, mean mode) and Emission of Solar Protons (ESP, 90 per cent confidence) models, and, together with mission duration, are mapped through reflection-paired membership partitions and a 27-rule sum-based rule base to four triage categories. We prove reflection symmetry of the input and output partitions, permutation symmetry of the rule map, risk-reversal duality of the aggregated inference and centroid score, and reflection equivariance of a normalised output-support vector retained before defuzzification. The architecture is examined on nine reference mission scenarios and additional boundary cases using sensitivity, comparative-variant and cumulative-versus-duration-normalised analyses. The results show exact algebraic consistency with the imposed symmetry identities and transparent rule-level traceability, while also revealing the small local non-monotonicity of the centroid score and formulation sensitivity in the seven-year GLONASS-like scenario. Under the integrated-exposure formulation, scores range from 0.381 for the polar low-Earth-orbit scenario to 0.892 for the geostationary orbit (GEO). Because the same nine scenarios also define the frozen normalisation anchors, this range is a reference-set demonstration rather than an out-of-sample result. Evaluation to date comprises internal mathematical-consistency checks, comparison with an author-defined conservative heuristic and concordance with a seven-member expert panel blinded to the model output but rating the same scenario descriptions; the system has not been validated against ground-truth radiation-hardness outcomes such as mission anomaly records or component-qualification results. Cases for which the integrated and duration-normalised diagnostics disagree are flagged for separate engineering analysis. The system is a reference-benchmarked proof-of-concept pre-screening method and does not replace project-specific TID, total non-ionising dose (TNID), single-event-effect, shielding or component-qualification analysis.