A stray light evasion method for star sensor

When star sensor is applied to spacecraft such as ballistic missile and satellites in near-Earth space, it is easily interfered by stray lights such as sunlight and moon light, which greatly reduces the signal-to-noise ratio of the star image and even submerges the star spot on the image. Regarding to the issues above, a stray light evasion method for star sensor is proposed. Firstly, taking the geocentric equatorial inertial coordinate system as the reference coordinate system, the condition that three main stray lights of sunlight, moonlight and geo-atmospheric light enter the field of view of star sensor is analyzed. Secondly, the reference optical axis of star sensor is established, which could evade three main stray lights at the same time. Finally, a fast and effective method of evading stray light for star sensor is proposed. The simulation results based on STK software show that the optical axis of the star sensor determined by the proposed method can ensure that the success rate of avoiding sunlight, moon light and geo-atmospheric light is 100% during the satellite operating period. The effectiveness of the proposed method has been verified.

Based on the relative position relationship between the sun position vector, moon position vector, and spacecraft position vector on the celestial sphere, the conditions for sunlight, moon light, and earth gas light entering the field of view of the star sensor are analyzed and modeled. On this basis, a star sensor optical axis reference direction that can avoid the influence of stray light is established, and further sorting out methods for star sensor stray light avoidance. Simulation experiments were conducted based on STK software, and the results showed that the optical axis orientation obtained by the proposed method can effectively avoid the influence of stray light on the star sensor. It is worth noting that the proposed method requires the strapdown carrier to have attitude adjustment capability, so that the optical axis of the star sensor can point towards the sky domain that can avoid stray light. Therefore, when applying star sensors to ballistic missiles, the missile attitude can be adjusted based on the results of the proposed method to obtain the optimal optical axis direction; In addition, the proposed method can also provide some guidance for the layout of multi star sensors on satellites.