GRACE 型重力卫星质心定标算法

In order to meet the observation conditions of the accelerometer, the offset between the center of mass of satellite and the accelerometer proof mass should not exceed 100 μm. However, many factors, such as the initial installation error, the stress release after the satellite in orbit, and the asymmetric consumption of cold gas between two tanks, will lead to the change of center of mass. Therefore, the calculation of satellite CoM-offset and the use of CoM-Trim to adjust satellite CoM are the guarantee for the successful operation of GRACE-type gravity satellites. This paper takes GRACE-FO as an example and proposes three algorithms to estimate the CoM-offset of GRACE-type gravity satellites simultaneously. Firstly, the satellite CoM-offset sequences is calculated based on angular velocity, angular acceleration and linear acceleration measured by accelerometer during GRACE-FO satellite attitude maneuvers for CoM calibration. Secondly, the satellite CoM-offset in X direction is estimated by Kalman filter algorithm based on the asymmetric consumption of cold gas between two tanks. Finally, because GRACE-FO is equipped with a Laser Ranging Interferometer, the Tilt-to-Length (TTL) coupling effect of the satellite by attitude change, the CoM-offset and the Vertex Point (VP) of the Triple Mirror Assembly can be observed indirectly during the CoM calibration maneuver, and the CoM-offset in the Y/Z direction can be obtained. Based on the above three algorithms, the CoM-offset sequences of GRACE-FO satellite since its launch is estimated. The effect of mutual verification has been achieved, and have a good agreement with the estimation results of JPL and CSR, indicating that the three CoM calibration algorithm adopted in this paper can be applied to the CoM-offset estimation of GRACE-type gravity satellites. At the same time, it is found that the Y-direction of satellite CoM-offset has a periodic fluctuation related to β angle (the angle between the solar vector and the orbital plane).