De-Orbit Low Thrust Optimization to Compute Rapid Orbit Lowering Trajectories

Orbit lowering is a long duration phenomenon with repeated revolutions and multiple eclipses are encountered along its trajectory. Spacecraft moving from an higher orbit to a lower orbit using a solar electric propulsion system posses a major challenge of long transfer time and degradation of solar array in Van Allen belt. The mathematical formulation of spacecraft used earlier for orbit raising is implemented for orbit lowering to bring the spacecraft to a lower orbit to reach the Earth's atmosphere and burn by optimizing the angular momentum and eccentricity to that of target orbit. This phenomenon is divided into many unconstrained sub-problems of optimization which perform the deviation gap minimization between geosynchronous equatorial orbit and a lower orbit.