A physics-informed framework for synthetic flyby imaging of activity in dynamically new comets

Abstract

ESA’s Comet Interceptor mission is designed to encounter a dynamically new, and likely previously undiscovered, long-period comet whose nucleus shape and activity state will be poorly constrained before arrival. We present a physics-informed framework for synthetic flyby imaging of cometary activity when the nucleus morphology and activity state are not known in advance. The framework combines a reduced-order model of the diffuse dust coma, a thermophysically motivated model for localized dust jets driven by water-ice sublimation, procedural generation of plausible irregular nucleus shapes, and physically informed volumetric rendering under instrument-specific observing geometry. The thermophysical component is evaluated against independent reference models, TEMPEST and ThermoONet, over a range of heliocentric distances, showing good agreement in the non-sublimating regime and reproducing the expected cooling trend when sublimation is included. For observational comparison, calibrated OSIRIS images are used as the primary reference, with corresponding Rosetta viewing geometries of comet 67P/Churyumov–Gerasimenko reconstructed from SPICE kernels to enable comparison with synthetic renderings. Across more than 60 matched observations, the framework improves agreement with the dominant large-scale image structure and produces activity-like signatures under matched observing geometry. Because the framework is modular, individual sub-models for thermal evolution, coma structure, or jet activity can be exchanged for higher-fidelity or target-specific alternatives while preserving the same synthetic flyby imaging framework.