A Novel High-Resolution Asteroid Imaging Method Based on Joint Estimation of Motion and Topography

Earth-based radar plays a critical role in high-resolution asteroid imaging. However, traditional methods often suffer from range-azimuth defocusing due to the rapid translational and complex rotational motion of asteroids. Moreover, integration across sub-apertures is required to improve the signal-to-noise ratio (SNR), which in turn demands accurate surface topography information. To this end, this paper proposes a novel high-resolution asteroid imaging method based on joint estimation of motion and topography. First, accurate translational parameters are estimated to mitigate the pulse-scale stretching effect (PSSE), thereby improving range focusing performance. A coarse-to-fine estimation for rotational parameters is then performed, starting with an initial estimate based on image-domain quality metrics, followed by aggregating information from multiple feature points to jointly estimate refined rotational parameters and local elevations. Finally, a coarse surface topography is reconstructed from the estimated elevations to support sub-aperture integration, resulting in a high-resolution image with enhanced SNR. The effectiveness of the proposed method is demonstrated through simulations and validated experimentally in a controlled microwave anechoic chamber.