Available at: https://digitalcommons.calpoly.edu/theses/2435
Date of Award
MS in Aerospace Engineering
College of Engineering
College of Engineering
Traditionally, two-body dynamics have been used to design orbital trajectories for interplanetary missions using a series of Lambert’s transfers and gravity assists. Although these are reliable methods, they have extremely high fuel requirements, especially for missions to outer planets. From an orbital mechanics perspective, three ways of reducing fuel requirements for these types of missions are utilizing low energy transfer trajectories, applying low thrust engine parameters, and implementing orbit optimization techniques.
The goal of this thesis is to combine low energy transfers created from the dynamics of the Circular Restricted Three-Body Problem (CRTBP) with low-thrust orbit optimization techniques to develop interplanetary missions that require less fuel to reach their destinations when compared to transfers that implement traditional two-body dynamics. A Patched Conics with Manifolds method was used to maneuver a spacecraft from low Earth orbit to a halo orbit and then use exterior manifolds to link a spacecraft along a low-thrust interplanetary trajectory between the halo orbits of Earth and the destination planet. Indirect and direct optimization are applied to both an initial orbit raising maneuver and the low-thrust interplanetary transfer to attempt to reduce the fuel requirements needed for each mission phase. These transfers are tested for missions from Earth to Jupiter and Earth to Saturn and the fuel requirements and time of flight are analyzed.
Results from this research showed that applying low thrust optimization to portions of the interplanetary transfer using manifolds reduced the fuel required for each phase of the transfer for both missions to Jupiter and Saturn. For the low thrust orbit raising phase, the fuel requirements were reduced by 13-17%, while for the interplanetary phase fuel requirements were reduced by 23-27% for the mission to Jupiter and 15- 17% for the mission to Saturn when compared to previous methods. In addition, additional fuel savings are found by the elimination of the need for a second stage to arrive at the destination planet due to the low-thrust maneuver accounting for the reduction in speed due to the constant burn throughout the interplanetary phase.
Analysis of the flight times for each test case showed that the Patched Conics with Manifolds method combined with low-thrust maneuvers increased the amount of travel time by 6.5 years for a mission to Jupiter and 8.5 years for a mission to Saturn. Overall, the fuel and time of flight results show that there is a trade-off between significantly reducing the fuel needed for this type of transfer and significantly increasing the transfer time that must be considered for each particular mission application.