Study
Study

Author: Oscar Calvente Lozano

Publisher:

Published: 2018

Total Pages:

ISBN-13:

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Nowadays, technology advances have given us the chance to achieve things that a couple generations ago could not even dream of. Space exploration is one of those achievements and space mission designing is a vital part of it. Since the firsts space missions, the methods used to design them have been increasingly evolving and sophisticating with time. Scheduling a space mission is a complex task that takes time and effort to achieve. A crucial factor to determine a space mission trajectory is cost, which is basically reflected in the fuel used to accomplish the mission. In order to reduce the quantity of propellant used in a mission, multi-gravity assists provide the capability to the spacecraft of altering its speed and path. Throughout this process, analysis to optimize the path of the mission are done. To do so, the optimizers need a list of planet sequences to start analyzing. A first approach to obtain viable lists of planets is using Tisserand graphs. The Tisserand graph is a graphical tool developed to aid in searching for paths for a space mission. The aim of this bachelor's thesis is to implement a code that uses a tree search algorithm to find viable multi-gravity-assist trajectories from a Tisserand graph in an automatic manner. Several versions of the code have been implemented until reaching a definitive version that fulfills the requirements of the thesis. The final version uses a depth-limited search algorithm to explore a search tree generated automatically in an iterative process from a Tisserand graph, storing in the process all the found flybys sequences.

Optimization of Low-thrust Spacecraft Trajectories by Direct Shooting Methods [microform]
Optimization of Low-thrust Spacecraft Trajectories by Direct Shooting Methods [microform]

Author: Christopher Rampersad

Publisher: Library and Archives Canada = Bibliothèque et Archives Canada

Published: 2004

Total Pages: 188

ISBN-13: 9780612951822

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The direct approach for trajectory optimization was found to be very robust. For most problems, solutions were obtained even with poor initial guesses for the controls. The direct approach was also found to be only slightly less accurate than the indirect methods found in the literature (within 0.7%). The present study investigates minimum-time and minimum-fuel low-thrust trajectory problems via a single shooting direct method. Various Earth-based and interplanetary case studies have been examined and have yielded good agreement with similar cases in the literature. Furthermore, new near-optimal trajectory problems have been successfully solved. A multiple-orbit thrust parameterization strategy was also developed to solve near-optimal very-low-thrust Earth-based transfers. Lastly, this thesis examines the use of the high-accuracy complex-step derivative approximation method for solving low-thrust transfer problems. For certain very nonlinear transfer problems, the complex-step derivative approximation was found to increase the robustness of the single shooting direct method.

Optimal Space Trajectories
Optimal Space Trajectories

Author: Jean-Pierre Marec

Publisher: Elsevier

Published: 2012-12-02

Total Pages: 356

ISBN-13: 0444601074

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Studies in Astronautics, Volume 1: Optimal Space Trajectories focuses on the concept of optimal transfer and the problem of optimal space trajectories. It examines the relative performances of the various propulsion systems (classical and electrical propulsions) and their optimization (optimal mass breakdown), along with parametric and functional optimizations and optimal transfers in an arbitrary, uniform, and central gravitational field. Organized into 13 chapters, this volume begins with an overview of optimal transfer and the modeling of propulsion systems. It then discusses the Hohmann transfer, the Hoelker and Silber bi-elliptical transfer, and the deficiencies of parametric optimization. The book explains the canonical transformation, optimization of the thrust law using the Maximum Principle, and optimal orbit corrections. The time-free orbital transfers and time-fixed orbital transfers and rendezvous are also discussed. Moreover, this volume explains the classical high-thrust and electric low-thrust propulsion systems and rendezvous between two planets. This book is written primarily for engineers who specialize in aerospace mechanics and want to pursue a career in the space industry or space research. It also introduces students to the different aspects of the problem of optimal space trajectories.

Optimization of Low Thrust Spacecraft Trajectories Using a Genetic Algorithm
Optimization of Low Thrust Spacecraft Trajectories Using a Genetic Algorithm

Author: Jason Corey Eisenreich

Publisher:

Published: 1998-01-01

Total Pages: 79

ISBN-13: 9781423554493

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This thesis concerns the use of genetic algorithms in the optimization of the trajectories of low thrust spacecraft. Genetic algorithms are programming tools which use the principles of biological evolution and adaptation to optimize processes. These algorithms have been found to be very useful in many different engineering disciplines. The goal of this project is to determine their applicability to the generation and optimization of low thrust spacecraft trajectories. This thesis describes the basic operating principles of genetic algorithms and then applies them to two different missions.