Inclination Perturbations of Polar-Orbit Satellites

摘要

This report describes an investigation of the ability to predict long-term orbital elements for medium-height (satellite orbiting the earth at altitudes above the regions of appreciable drag), earth-orbiting satellites. The particular types of satellites studied are those having nearly circular, polar orbits. The primary element of interest is orbital inclination. A theoretical equation for predicting the change in inclination caused by the gravitational attraction of the sun and moon is given. Expressions for the orbital elements of the sun and moon required in this inclination-predicting equation are developed. A FORTRAN program listing and computation procedure for determining the inclination of a satellite at any time after a chosen epoch is in the appendix. Nine satellites were selected for study. For these satellites, comparison plots of observed and predicted inclinations over a 3-year time interval are shown. The agreement between predicted and observed inclinations is very good for most of the satellites. Theoretical plots of the inclination of Satellite 902 over time intervals of up to 300 years are included. (Author)