Delta-V gravity-assist trajectory design: Theory and practice

Jon Andrew Sims, Purdue University

Abstract

The thesis consists of theoretical developments and practical applications in interplanetary trajectories for the purpose of minimizing launch energy and propellant requirements. Analytic techniques are developed to predict potentially useful trajectories and create innovative trajectories. Advanced software is used to find and optimize trajectories to important scientific targets, thereby validating the techniques. The principal theoretical work is the development of an analytic theory for $V\sb{\infty}$ leveraging--the use of a relatively small deep-space maneuver to modify the V$\sb\infty$ at a body. This maneuver, in conjunction with a gravity assist at the body, reduces the launch energy requirements and the total $\Delta$V for a mission. A typical example of V$\sb\infty$ leveraging is the $\Delta$V-EGA ($\Delta$V-Earth Gravity Assist) trajectory. The general theory of V$\sb\infty$ leveraging is extended from exterior, single-revolution $\Delta$V-EGAs to include multiple-revolution $\Delta$V-EGAs, interior $\Delta$V-EGAs, and $\Delta$V-VGAs ($\Delta$V-Venus Gravity Assists). The theory is applied to find many different types of trajectories to numerous celestial bodies--particularly Pluto, asteroids, and Saturn. In some cases trajectories are found in which the deep-space $\Delta$V is replaced by a gravity assist. In an aerogravity assist, a lifting body flies through the atmosphere of a planet to enhance the pure gravity assist. A thorough analysis of the trajectory space for low launch energy trajectories to the outer planets with aerogravity assists at Venus and Mars in succession, and at Mars alone, is performed. The results of this analysis demonstrate the ability of aerogravity assists to significantly reduce the required launch energies and flight times to the outer planets. An analytic approach for an initial assessment of the effect of drag on aerogravity-assist trajectories is developed. The analyses of V$\sb\infty$ leveraging and aerogravity assists are combined in an investigation of $\Delta$V-EAGA ($\Delta$V-Earth AeroGravity Assist) trajectories. A general methodology for mission design is established and proves to be a very efficient and thorough means of finding many different types of trajectories for a wide range of missions. By minimizing launch energy and propulsive requirements, smaller, less costly launch vehicles and larger, more scientifically capable spacecraft can be used.

Degree

Ph.D.

Advisors

Longuski, Purdue University.

Subject Area

Aerospace materials

COinS