A paper describes a computationally efficient method of optimizing trajectories of spacecraft driven by propulsion systems that generate low thrusts and, hence, must be operated for long times. A common goal in trajectory-optimization problems is to find minimum-time, minimum-fuel, or Pareto-optimal trajectories (here, Pareto-optimality signifies that no other solutions are superior with respect to both flight time and fuel consumption). The present method utilizes genetic and simulated-annealing algorithms to search for globally Pareto-optimal solutions. These algorithms are implemented in parallel form to reduce computation time. These algorithms are coupled with either of two traditional trajectory- design approaches called "direct" and "indirect." In the direct approach, thrust control is discretized in either arc time or arc length, and the resulting discrete thrust vectors are optimized. The indirect approach involves the primer vector theory (introduced in 1963), in which the thrust control problem is transformed into a co-state control problem and the initial values of the co-state vector are optimized. In application to two example orbit-transfer problems, this method was found to generate solutions comparable to those of other state-of-the-art trajectory-optimization methods while requiring much less computation time.
This work was done by Seungwon Lee, Wolfgang Fink, Ryan Russell, Richard Terrile, Anastassios Petropoulos, and Paul von Allmen of Caltech for NASA's Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Mechanics/Machinery category.
The software used in this innovation is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-42975.
This Brief includes a Technical Support Package (TSP).
Efficient Optimization of Low-Thrust Spacecraft Trajectories
(reference NPO-42975) is currently available for download from the TSP library.
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Overview
The document titled "Efficient Optimization of Low-Thrust Spacecraft Trajectories" (NPO-42975) is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) that discusses advancements in optimizing spacecraft trajectories using low-thrust propulsion systems. It is part of NASA's Commercial Technology Program, aimed at disseminating aerospace-related developments with broader technological, scientific, or commercial implications.
The primary focus of the document is on the application of the Primer Vector Theory, which is a mathematical framework used for trajectory optimization. This theory allows for the efficient planning of spacecraft paths, particularly for missions that require low-thrust propulsion, such as those involving electric or ion engines. These propulsion systems are characterized by their ability to provide continuous thrust over extended periods, making them suitable for deep-space missions where fuel efficiency is critical.
The document outlines various optimization techniques, including parallel, global, and Pareto optimization methods. These approaches are designed to enhance the efficiency of trajectory planning by considering multiple objectives simultaneously, such as minimizing fuel consumption while maximizing mission success. The use of advanced computational techniques enables the handling of complex trajectory scenarios and the exploration of a wide range of potential mission profiles.
Additionally, the Technical Support Package emphasizes the importance of collaboration and innovation in aerospace technology. It provides contact information for further inquiries and assistance, specifically through the Innovative Technology Assets Management at JPL. This reflects NASA's commitment to fostering partnerships and sharing knowledge within the aerospace community.
The document also includes a notice regarding the proprietary nature of the information contained within, indicating that it may be subject to export control regulations. This highlights the sensitive nature of aerospace technology and the importance of compliance with applicable laws.
In summary, the document serves as a comprehensive resource for understanding the methodologies and technologies involved in optimizing low-thrust spacecraft trajectories. It underscores the significance of efficient trajectory planning in the context of modern space exploration and the potential applications of these advancements in various aerospace endeavors.
