Date of Award


Degree Name

MS in Aerospace Engineering


Aerospace Engineering


Kira Abercromby


For a detailed analysis of orbital optimization, it is desired to incorporate a spacecraft environment model in order to have maximum confidence that the analysis will produce an accurate trajectory. Such a model requires the addition of orbital perturbations, or small forces acting on the spacecraft throughout its trajectory that can eventually accumulate in large distances over time. The optimization method that this thesis is concerned with is STOpS (Spacecraft Trajectory Optimization Suite), a Matlab optimizer created by Timothy J. Fitzgerald that utilizes an Island Model Paradigm with five different optimization algorithms. STOpS was originally built to model trajectories with the two body equations of motion. A Lambert's method was utilized to link the spacecraft trajectory from planet to planet, and a flyby section was created for the hyperbolic gravity assist trajectories. A cost function was then used to evaluate the best combination of Delta V, time of flight, synodcity, flyby altitude, and heliocentric energy. This work is primarily concerned with adding the dynamics created by perturbations into Lambert's problem as well as the gravity assist trajectories. The improved analysis creates a more robust solution for dealing with optimized interplanetary trajectories. Two proven trajectories will be focused on for the main analysis of this thesis which are the trajectories taken by Voyager 2 in the tour of the solar system as well as Cassini's mission to Saturn. When perturbations were added to the analysis of these missions, STOpS was able to find trajectories which met both Delta V and time of flight requirements for each mission. For the optimization of each of these missions the key dates of departure, flyby, and arrival at all the planets varied by no more than one year from the true trajectories of Voyager 2 and Cassini.