Accession Number : ADA189574

Title :   Frozen Orbit Analysis in the Martian System.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Foister, James W , III

PDF Url : ADA189574

Report Date : Dec 1987

Pagination or Media Count : 189

Abstract : A frozen orbit is an orbit whose time rate of change of the argument of the periapsis, the eccentricity, the semi major axis, or the angle of inclination (i) is approximately equal to zero. Martian frozen orbits are known to exist for polar trajectories with altitudes from 300 km to 1000 km. The objective of this study was to determine if other regions with characteristics similar to the known frozen orbits exist, taking into account the perturbative effects due to a 6 X 6 gravity field and atmospheric drag. First, the geopotential equation was derived for both spherical coordinates and the classical orbital elements. Next, a model for the atmospheric drag was developed. Using these two models, a Fortran computer model named ASAP (Artificial Satellite Analysis Program) was analyzed for accuracy. This program proved to be highly reliable, and was used to carry out further analysis. Two of the three trajectories planned for the future Mars Geoscience/Climatology Orbiter (MGCO) are frozen orbits. In order to determine the characteristics of w, e, a, and i of a frozen orbit, one of the MGCO frozen orbits was examined in both a 6 X 0 and a 6 X 6 gravity field. The analysis showed that the above orbital elements are not periodic over one orbital period (when in the presence of a 6 X 6 gravity field), but they are bounded over one axial period.

Descriptors :   *MARS(PLANET), *ORBITS, *CELESTIAL MECHANICS, *POLAR ORBIT TRAJECTORIES, ACCURACY, AERODYNAMIC DRAG, ANGLES, ARTIFICIAL SATELLITES, ATMOSPHERIC DENSITY, COMPUTERIZED SIMULATION, EQUATIONS, FORTRAN, GEOPOTENTIAL, RATES, SLOPE, THESES, TIME, STEADY STATE, PERTURBATIONS

Subject Categories : Celestial Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE