Implementing a 50x50 Gravity Field Model in an Orbit Determination System
Abstract
The Kepler problem treats the earth as if it is a spherical body of uniform density. In actuality, the earth's shape deviates from a sphere in terms of latitude (described by zonal harmonics), longitude (sectorial harmonics), and combinations of both latitude and longitude (tesseral harmonics). Operational Orbit Determination (OD) systems in the 1960's focused on the effects of the first few zonal harmonics since (1) they represented the dominant terms of the geopotential perturbation, (2) they were well known, and (3) the use of a limited number of harmonics greatly simplified the perturbation theory used. The demand for increasingly accurate modeling of a satellite's motion, combined with an increase in knowledge of the geopotential and an advancement in computer technology, led to the inclusion of tesseral harmonics. The Draper Laboratory version of the Goddard Trajectory Determination System (R&D GTDS), one operational OD system, can currently implement up to a 2lx2l gravity field model in its Cowell and Semianalytic Satellite Theory (SST) orbit generators. This thesis investigates the extension of R&D GTDS to include a 50x50 gravity field model in the Cowell and SST orbit generators. This extension would require code modifications in the following environments to support the various operational versions of R&D GTDS: IBM, VAX, Sun Workstation, and Silicon Graphics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1993
- Accession Number
- ADA267548
Entities
People
- Daniel J. Fonte Jr.
Organizations
- Air Force Institute of Technology