1 Semi-analytical Method for Active Removal of Space Debris with Electrodynamics Tether System Yehia Abdel-Aziz 1 , Islam M. Hawash 1 , A. M. Abdelaziz 1 and Ayman M. Mahrous 2,3 1 National Research Institute of Astronomy and Geophysics (NRIAG), 11421-Helwan, Cairo, Egypt 2 Egypt-Japan University of Science and Technology (E-JUST), Cairo, Egypt. ,3 Helwan University, Cairo, Egypt. yehia@nriag.sci.eg Abstract: Growing the number of space debris has recently become a topic of eminent concern. Therefore, orbital debris removal has become a very grave issue for both of scientific and commercial space management in order to avoid loss any operational satellite. To prevent loss of spacecraft due to debris collision, it is very essential to address the aggregate risk which need an efficient way to remove or avoid collision with operating satellites. This work develops a semi-analytical method for orbital decay using Electrodynamics tether system (EDT) as a technique of active debris removal to avoid collision with operational satellites. This efficient method can change the orbit of a satellite to be more elliptical in near polar orbits due to the higher-order perturbation of Earth’s magnetic field and Lorentz force. Gaussian form of Lagrange Planetary equations is used to evaluate the orbital motion of EDT with environmental perturbations of electrodynamic force, aerodynamic drag and the effect of Earth’s oblateness. Differential equations for the induced voltage-current across EDT are derived and solved with boundary conditions determined by mission objectives and duration of the deorbit. The change in electric current in the EDT due to its plasma environment and thermal conditions are considered. Analyses of different parameters of EDT dynamics with variations in the mass, type of the materials of the wire of tether, and the tether length were studied to classify the range of eccentricity of the elliptical orbit for possibility of deorbit the desired missions. Applied the current model of the EDT find that the orbit of a satellite deorbited will become elliptical in near polar orbits due to the higher-order perturbation Earth’s magnetic field and Lorentz force. The effects of polarity on reverse of the induced voltage/current across EDT in near polar have been discussed. Comparison between air drag only EDT for orbital decaying time in case of equatorial and polar orbit are introduced. Introduction: Space debris has recently become a topic of elevated interest [1] Currently, there are more than 17,000 space objects in the catalog of the United States Space Surveillance Network (SSN) [2] , with only about 1,200 being active satellites. [3] A collision threat emanates from all the other, inactive a Space debris has recently become a topic of elevated interest [1] currently, there are more than 17,000 space objects in the catalogue of the United States Space Surveillance Network (SSN) [2] , with only about 1,200 being active satellites. [3] A collision threat emanates from all the other, inactive and uncontrollable objects: The space debris. [1] The only natural self- cleaning mechanism in the near-Earth space is the residual atmospheric drag. However, the orbital lifetime of objects beyond 400 km is measured in decades or centuries. Therefore, it is likely that an object eventually collides with another object. [1] It is too late for simply stopping the littering, as it will not necessarily stop the debris population from growing. Moreover, launching heavily armored satellites is impractical for a variety of reasons: Shielding increases the systems' complexity, the launch masses, and the costs. Not all parts of a satellite can be shielded for technical reasons, and a lethal collision can never be ruled out. Besides, the additional shielding mass could end up as DOI: 10.13009/EUCASS2019-532