TABLE OF CONTENTS This chapter provides a description of each of the perturbation forces and considers the actual applications to mission design and analysis of Earth satellite missions. The various perturbation forces are: Earth's oblateness and its triaxiality, the lunisolar gravitational attractions, the solar-radiation pressure, the Earth atmospheric drag, and the tidal friction effects. The interesting properties of orbits with critical inclination (Molniya orbit), sun-synchronous orbits, frozen orbits, and the long-term coupling between sun-moon attractions and Earth oblateness effects will be discussed.
The principal effects of the J 2 zonal harmonic or Earth's oblateness are secular motions of the node ? and perigee ? of an orbit. The westward rotation of the orbit plane is illustrated in Fig. 10.1, where S denotes the longitude difference between two successive crossings of the equator.
The motion of the node ? occurs because of the added attraction of the Earth's equatorial bulge, which introduces a force component toward the equator. The resultant acceleration causes the satellite to reach the equator (node) short of the crossing point for a spherical Earth. The orbit thus regresses a delta node ( ? ?) each revolution. This effect may also be regarded as gyrodynamic precession due to a torque acting on the satellite angular momentum vector caused by the additional attraction of the Earth's equatorial...
