提高低轨道卫星预报精度的一个方法

为了提高卫星预报精度，采用了与其他人不同的方法，从ＩＲＶ资料（欧洲提供预报的卫星三维坐标和速度分量的资料；使用的坐标系随着地球运动，ｘ轴指向地球经度零点）求出初始轨道根数用多圈ＩＲＶ资料或ＳＬＲ（卫星激光测距）资料进行轨道改进求出更好的轨道根数ａ，ｉ，Ω、ζ＝ｅ ｓｉｎω，η＝ｅｃｏｓω和ｌ＝Ｍ＋ω。与三维坐标和速度相比，用这些轨道根数作为数值积分基本变量，可减少内插多项式的次数。本法的ｘ轴指向平

A Method to Improve the Accuracy of Low Orbit Satellite Prediction

To improve the accuracy of satellite prediction, a method differred from others is adopted The primary orbit elements are derived from IRV data (predicted 3-dimension coordinate of the satellite and velocity components provided by Europe; coordinate system used rotates with the Earth, while x- axis directs to the longitude zero-point in the Earth). Better orbit elements a、i、Ω、ξ=e sinω,η=e cosω and l=M+ω are derived from orbit improvement by multi-pass IRV data or SLR (satellite laser ranging) data.By using these orbit elements as basic variables in numerical integration,it is possible to reduce the degree of the polynomial of the interpolation comparison with 3-dimension coordinate and velocity components. In this method x- axis directs to Mean Equinox, so as to decrease the influence of the error in the predicted correction of universal time UT1-UTC. The usage of up date SLR data can improve the orbit elements of satellites. When prediction, computed order and degree of the Earth's spherical harmonic perturbation are extended to 20×20;the accuracy of computed solar and lunar coordinates is improved to about 2',to further improve computation accuracy of solar and lunar perturbations. The light pressure perturbation, the atmosphere drag perturbation, and the influences of the coordinate system and the polar motion transformation are also taken into account. The improved satellite prediction procedure would be available to the SLR in daytime. This method has been programmed and carried out by microcomputer 486/66 in Shanghai Observatory SLR station. By only 1 manipulafion,it can carry out all computation including initial orbit elements, data procession and filtering, the computations of various perturbations on the satellites, the numerical integration, the orbit improvement, interpolation and the fast computation of the visual topocentric coordinate of the satellites.