Measurement of noncooperative spacecraft components using multistatic spaceborne radar and optical images

Attitude and size estimation of spacecraft components is one of the main contents of space target awareness. In this paper, a radar-camera joint observation scheme applicable to multiple spaceborne platforms is developed to measure the orientation and length of the spacecraft solar panels, which benefits from the observation diversity jointly provided by radars and cameras. Firstly, an automatic keypoint detection network is trained to extract the endpoints of the solar panels in the radar and optical images with high accuracy. Then, the projected lengths of the solar panels calculated from the extracted endpoints along with the observation equations of the radars and cameras are jointly used to obtain the orientation and actual length of the solar panels by an optimization approach. Simulated experiments are conducted to demonstrate the performance of the proposed measuring methods, which achieves length estimation errors within 0.2 m and orientation estimation errors within 1°. The proposed method can be extended to the measurement of main body and other spacecraft components having regular features.