Rubble pile asteroid radar analogue model for Dimorphos — The asteroid moon of 65803 Didymos

Understanding the internal structure of rubble pile asteroids is crucial for studies of Solar System evolution, effective planetary defense, and asteroid resource utilization. This study presents a method for controlling the volume fraction and overlap of multiple ellipsoidal particles to generate a physical rubble-pile analogue model with target permittivity properties and internal structure for laboratory experiments and to distinguish internal structural features in tomographic backscattering radar data. This work supports tomographic radar exploration of Dimorphos, the moonlet of asteroid 65803 Didymos, targeted by ESA’s Hera mission and the Juventas Radar (JuRa) aboard the Juventas CubeSat. We created three alternative synthetic models that were 3D-printed using permittivity-controlled ABS plastic in a fused filament fabrication (FFF) process. These models comprise a varying internal structure and porosity, reflecting recently observed parameters of Dimorphos’ boulder size, eccentricity and porosity distributions. Additionally we generated three spherical models with attributes matching the Dimorphos-shaped analogues in order to get a better understanding of the permittivity and wave propagation for this kind of structure. The structural composition of the analogue models was numerically analyzed in terms of effective permittivity and compared with the observational data of Dimorphos. To approximate the effective permittivity of the porous object, we use Maxwell Garnett and Looyenga models. Results indicate that the proposed method for generating analogue models accurately replicates the properties of the real asteroid body, suggesting that these 3D printed surrogates provide key insights for future space missions.