Automatic Dynamic Estimation of On-Orbit Satellites Through Spaceborne ISAR Imaging

With the continuous development of satellite constellations worldwide, dynamic estimation of on-orbit spacecraft plays a more and more important role in space situation awareness applications. Based on high-resolution inverse synthetic aperture radar (ISAR) imaging from the ground, some exploratory methods have been proposed to estimate target dynamic parameters, such as its attitude pointing and spin period. Due to the limited observation view from the ground, most of them rely on the long-term measurement, and the robust association of image features needs to be ensured. In this article, a novel approach based on spaceborne ISAR images is proposed to achieve the dynamic estimation of spin satellites. In order to build a synchronous similar-resolution ISAR imaging system, two adjacent satellites are picked up from low earth orbit constellations according to the radar tracking parameters. With obtained a pair of ISAR images, the explicit expression between target dynamic parameters and projection feature is deduced. Inspired by the existing works on shape extraction of the human body, a feature extraction network is built on the framework of ResNet for achieving the automatic processing in spaceborne equipments. In this way, target dynamic parameters can be solved in instantaneous attitude optimization and spin motion optimization in steps. Simulation experiments of a typical spin spacecraft, Tiangong-I, illustrate the feasibility of the proposed method. Besides, a comparison experiment with an existing ground-based work is also made to analyze its advantage in practical applications.