Analytical generation of orbits at the royal aircraft establishment

Abstract

This paper traces the development of the main computer programs for analytical orbit determination and orbit evolution carried out at the RAE. The principal program, PROP, is still in regular use, having an accuracy of 50 to 100 m for the orbits of close satellites determined over a period of a few days even when the drag is severe. The chief limitation of PROP is the absence of lunisolar perturbations, but these are included in a companion program, PROD, for the evolution of mean elements. Work of recent years has focused on a framework for far more accurate representation and generation of orbits. The method is purely analytical (as in PROP) for short-period perturbations, applied compactly via the use of a special system of spherical coordinates, but employs a degree of numerical integration in the variation of mean elements. The goal is a single program that would eventually supersede the PROP-PROD combination, providing an accuracy of perhaps 1 m.