Perturbations in rectangular coordinates by iteration

An investigation has been made on computing orbits with Picard's method of successive approximations. The perturbations are integrated in the form of a general displacement from a fixed Keplerian reference orbit. Several variation-of-parameters methods are obtained for the integration of the displacement equation. These variation-of-parameters methods could be used as special perturbation or general perturbation methods. The present paper investigates the applications as iterative numerical perturbation techniques. Four different formulations are proposed. They have been implemented on a computer with Chebychev series and their respective advantages and disadvantages are analyzed. Connections with other known perturbation methods are also described.This paper presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract No. NAS 7-100, sponsored by the National Aeronautics and Space Administration.