Research On Measurement Method Of Upper Atmospheric Density Based On Precision Orbit Of A Spherical Satellite

The Earth's atmosphere is an important part of the near-Earth space environment.The atmospheric drag force is the dominant non-conservative perturbation force acting on LEO satellites.Therefore,the determination and prediction of the atmospheric density is crucial for the spacecraft trajectory prediction,the collision risk warning and the uncontrolled spacecraft falling.Satellite measurement is increasingly used in the detection of upper atmospheric density.Based on the spherical-structured Tsinghua scientific satellite on-orbit mission,this paper studies the atmospheric density measurement method based on satellite precision orbit data.It mainly includes the following aspects:Aiming at the complex variation characteristics of atmospheric density due to various factors,a measurement method based on the precision orbit data to calibrate the atmospheric density model is proposed to improve the estimation accuracy and prediction accuracy of atmospheric density.Combined with the characteristics of high precision and continuity of the spherical satellite precision orbit data,a dynamics method for parameter calibration is designed.According to the requirements of the method,the Harris-Priester atmospheric density semi-empirical model for direct parameterization of atmospheric density values was selected,and the modeling of model daily density extreme parameters was linearly adjusted to ensure the accuracy of calculation,which improves the computational efficiency of the method.According to the on-orbit dynamics model of LEO spacecrafts,the influence of perturbation forces,especially the gravity field rounding error and model error,on the estimation error of atmospheric density is analyzed,and the error transfer relation is established.Based on the orbit determination error of Tsinghua Science Satellite,the influence of precision orbit determination error on density estimation error is analyzed,and the error magnitude transfer relationship is established.Using the simulated precision orbit data,the large-scale numerical simulation method was used to verify the parameter dynamics calibration process of the semi-empirical atmospheric density model.Different design parameters are selected for simulation,and the influence of the parameters on the correction results is analyzed.The results show that the model parameters can converge well for the orbits below 500 km,and the sun-synchronous orbit is the best orbit type.The value of the integral arc length in the process has a great influence on the parameter convergence and model prediction accuracy.The results show that for the Tsinghua scientific satellite atmospheric density detection task with a fixed orbit error of 5 cm,the order of average prediction error of the atmospheric density is 10^-15kg·m^-3.