Passive Attitude Estimation of Spacecraft Based on Multiretroreflector Differential Satellite Laser Ranging

Passive attitude estimation of spacecraft is both the focus and the difficulty in space situational awareness. Solutions based on photometry usually require complex scattering characteristics modeling, while solutions based on radar imaging have bottlenecks in feature extraction and association. In this article, a new attitude estimation scheme is described based on satellite laser ranging (SLR) technology using corner-cube retroreflectors (CCRs) as beacons. The ground station simultaneously tracks multiple CCRs on the spacecraft and distinguishes the ranging signals to obtain high-precision range difference sequences containing complete attitude information. For this multi-CCR differential SLR (DSLR), we establish a complete set of methods for attitude inversion using range difference sequences. First, geometric measurement models are established to determine the relationship between the range difference sequence, the line-of-sight (LOS) direction, and the 2-D projection distribution of CCRs. Second, assuming that the object rotates around a fixed axis, analytical methods for determining the initial value of the attitude based on the LOS direction are established. Finally, considering the dynamic model error in real spacecraft rotation, a minimum model error (MME) batch-estimation approach is adopted for initial value correction. The proposed methods determine the initial value for state estimation through analytical calculation, reduce the large number of iterations required for multiparameter traversal in numerical calculation, and, thus, improve the computational efficiency. Based on the above methods, single short-arc ranging data of the defunct CZ-2C R/B with multi-CCRs were processed, and the rotation state trajectory satisfying the precession law was obtained.