Precision Improvement And Application Of LEO Space Objects Orbit Prediction

With the development of human space activities and space exploration technology, the population of space object is increasing and space debris has serious hazards to spacecrafts, so study on orbit prediction and collision warning becoming very important. In this paper, based on TLE+SGP4 model, a method to improve the orbit prediction precision of LEO space objects is proposed, and a dangerous conjunction analysis method is studied.Analysis on orbit prediction error shows that atmospheric density variations during space environment disturbance could cause large orbit prediction error on LEO space objects. Orbit prediction precision improvement method by modifying the drag coefficient with space environment induces is proposed in this paper. As atmospheric density variations in extrapolation process are concerned in this method, contribution of aerodynamic drag to the orbit is well reflected. Neural network is build for drag coefficient correction by using F10.7 and Ap induces, and result shows that neural network model could timely response to space environment disturbance. For higher temporal resolution during geomagnetic disturbance, application of auroral hemispheric power data (PH) is discussed. According to linear regression analysis, correction formulas for semi-major axis decrease and drag coefficients are proposed. This method is applied in orbit prediction of different height objects in different years, and in generally, semi-major axis prediction error is reduced about 50%, and position prediction error is reduced about 30%.A new method based on random point simulation to calculate the collision probability by using the position, velocity and prediction error information is proposed in this paper. Compared with the traditional method, the effects of error bias is concerned, which means the error ellipsoid no longer center on the predicted position. Results show that the maximum collision probability no longer appear in the time of closest approach. Process collision probability can be calculated by using the relative velocity assumes, and case analyses verify its validity. Furthermore, "space debris collision probability calculation and warning system" is designed. Six key technologies are resolved in this paper, which include orbital abnormal screening, error ellipsoid parameter generation, dangerous conjunction screening, collision probability calculation, fragmentation simulation and safety launch window analysis.Relationship between the sunspot numbers, Meiyu precipitation, and the west Pacific subtropical high induces are studied by using wavelet analysis and cross wavelet analysis method. Results show that the process chain of solar activity--Western Pacific subtropical high--Meiyu precipitation may exist in the influence of solar activity on the climate. Ionospheric anomalous disturbance during convective weather was investigated by using sliding mean method, and the ionospheric total electron content increased abnormally when convection occurred. Tropospheric vertical velocity is also analyzed to discuss the possible mechanisms of troposphere-ionosphere coupling.