The large field survey optical telescope system has strong spatial target information acquisition capabilities. Wide-angle telescope array as a typical large-field survey optical telescope system, can be used for the general survey of space targets, access to important parameters such as orbital parameters and shape and size parameters, is a powerful tool to grasp the spatial situation. In order to analyze the tracking effect of the wide-angle telescope array on the typical orbit of the space target and explore the best use scheme, this paper designs different combinations of field of view for the space configuration and geometric characteristics of the typical orbit of the space target. Simulate the census capabilities of the wide-angle telescope array. First, establish a typical orbit model for space targets. In the database, the data of the typical orbital parameters of the space target are collected, typical orbital parameters are selected according to the data characteristics, and a typical orbital model is constructed. Second, design the field of view combination. According to the data characteristics of different orbital parameters, different visual angles of wide-angle telescope arrays are designed. Finally, simulation census capabilities. The ability to determine the orbit and the time required for the census are taken as important indicators of the census capability. The census capabilities of the combination of field of view methods under different typical orbit conditions are simulated. The simulation results show that the wide-angle telescope array has a very strong census capability. Designing different combinations of field of view for different orbital features can improve the orbit determination accuracy of the wideangle telescope array, and at the same time greatly improve census capabilities.
Aiming at the three-axis stabilized geosynchronous orbit (GEO) satellites, a satellite working state detection method based on the photometric reflection characteristics is proposed. Firstly, the characteristics of the bidirectional reflection distribution function of the commonly used materials on satellite are analyzed. The amplitude variation characteristics and the beam widths of the specular reflection of the materials are discussed based on one modified Phong BRDF model. Secondly, the GEO satellite photometric observation equations are analyzed. The photometric characteristics of the satellites caused by solar motion and the duration of the satellite specular reflection under normal working conditions were quantitatively analyzed and the duration is then put forward as a quantitative judgment basis for working state of GEO satellite. Finally, Simulation results indicate that the detection method under the criteria we proposed can accurately determine whether the satellite is working normally or not. The method proposed can be used as a basis for detecting the working state of GEO satellites quickly which could be useful for space situation awareness.
In order to solve the problem of poor effect in modeling the large density BRDF measured data with five-parameter semi-empirical model, a refined statistical model of BRDF which is suitable for multi-class space target material modeling were proposed. The refined model improved the Torrance-Sparrow model while having the modeling advantages of five-parameter model. Compared with the existing empirical model, the model contains six simple parameters, which can approximate the roughness distribution of the material surface, can approximate the intensity of the Fresnel reflectance phenomenon and the attenuation of the reflected light’s brightness with the azimuth angle changes. The model is able to achieve parameter inversion quickly with no extra loss of accuracy. The genetic algorithm was used to invert the parameters of 11 different samples in the space target commonly used materials, and the fitting errors of all materials were below 6%, which were much lower than those of five-parameter model. The effect of the refined model is verified by comparing the fitting results of the three samples at different incident zenith angles in 0° azimuth angle. Finally, the three-dimensional modeling visualizations of these samples in the upper hemisphere space was given, in which the strength of the optical scattering of different materials could be clearly shown. It proved the good describing ability of the refined model at the material characterization as well.
In order to solve the problem that the movement state analysis method of the space target based on OCS is not related to the real motion state. This paper proposes a method based on OCS for analyzing the state of space target motion. This paper first establish a three-dimensional model of real STSS satellite, then change the satellite’s surface into element, and assign material to each panel according to the actual conditions of the satellite. This paper set up a motion scene according to the orbit parameters of STSS satellite in STK, and the motion states are set to three axis steady state and slowly rotating unstable state respectively. In these two states, the occlusion condition of the surface element is firstly determined, and the effective face element is selected. Then, the coordinates of the observation station and the solar coordinates in the satellite body coordinate system are input into the OCS calculation program, and the OCS variation curves of the three axis steady state and the slow rotating unstable state STSS satellite are obtained. Combining the satellite surface structure and the load situation, the OCS change curve of the three axis stabilized satellite is analyzed, and the conclude that the OCS curve fluctuates up and down when the sunlight is irradiated to the load area; By using Spectral analysis method, autocorrelation analysis and the cross residual method, the rotation speed of OCS satellite in slow rotating unstable state is analyzed, and the rotation speed of satellite is successfully reversed. By comparing the three methods, it is found that the cross residual method is more accurate.