3D full-waveform inversion of asteroid interior from monostatic radar data and its implications for acquisition geometry optimization

Understanding the interior structure and lithology of asteroids is crucial for gaining insights into their origin and evolution. The European Space Agency’s (ESA) Hera and China’s Tianwen-2 asteroid missions will employ monostatic orbital radar to investigate the interiors of the target asteroids Dimorphos and 2016 HO3, respectively. While most previous studies have focused on imaging asteroid interiors using bistatic radar data, relatively few have explored the same task using monostatic radar data (MRD). To support the measurement strategy and upcoming data processing for the two missions, it is essential to investigate potential imaging methods for reconstructing asteroid interiors from MRD. In this study, we propose a three-dimensional (3D) full-waveform inversion (FWI) approach to obtain the internal structure and permittivity distribution from MRD. Numerical experiments on 3D rubble pile and onion shell asteroid models validate the feasibility and accuracy of the proposed method. Additionally, a sensitivity analysis is performed using the 3D onion shell model to assess the influence of three factors—radar measurement points, number of orbits, and distance between adjacent orbits—on the FWI results. This study offers an effective approach for imaging asteroid interiors using MRD and provides valuable insights for optimizing acquisition geometries in future asteroid missions.