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NON-SPHERICAL EARTH EFFECTS ON THE GROUND TRACK SATELLITES AT DIFFERENT ALTITUDES

Ardhan Y. Omar Technical Eng. College, Kirkuk, Northern Technical University, Iraq.
Ahmed K. Izzet Technical Eng. College, Kirkuk, Northern Technical University, Iraq

Abstract

We address axisymmetric and stationary situations where there are perturbations of satellite orbits in the gravitational field of a body with a mass monopole and arbitrary spin multipole moments. The non-uniform mass distribution of the Earth causes gravitational forces for satellites operating in low-Earth orbits (LEO). All perturbation forces that affect the orbital elements also affect the satellite's ground track because it is connected to the orbital parameters. The importance of satellite systems in many facets of modern life has grown. By assessing various factors related to the use of the aforementioned systems and optimizing their benefits, the studies for achieving the intended aims can be realized. Placing the satellites in certain orbits that will deliver the appropriate features is crucial to achieving the anticipated aims. Another crucial task for the satellites is to maintain their orbits while maintaining their properties when they have reached such orbits. The perturbations influencing the satellites in their orbits are intended to achieve this goal, such as the harmonic coefficients Jn for the geopotential effect, must be accurately taken into account when choosing the appropriate orbits and locations. One of the most significant perturbation effects influencing the satellites' orbits and ground tracks is the J2 effect, also known as the attraction flattening and brought on by the Earth's dynamic oblateness. The impact It is impossible to ignore the non-spherical gravitational perturbations on Earth. during the repeat-ground track orbit design process; in other words, Earth is not able to regarded as an ideal sphere. The study reveals that disturbances can significantly alter satellite tracking, with a noticeable difference observed when satellites reach 1000 periods. The impact of disturbances on the satellites' ground track grows as the period of their orbit around Earth increases. The satellite's susceptibility to disturbance decreases with height and becomes more sensitive as the number of periods increases. The  appear more scrunched as the satellites approach Earth's rotation. This is essentially due to the fact that we are getting closer to  appears motionless because to the The rotation of Earth. in a 24-hour orbit with respect to the Earth's surface.

Keywords

Earth's Oblateness, Perturbations, Orbital elements, ground track,