TABLE OF CONTENTS Having considered one-, two-, and three-impulse ? V optimal transfers between orbits in Chapter 5, we now turn our attention to the complications of the real world. Are there cases in which four or more impulses would offer significant savings? Do we always want to use the ? V optimal transfer? How bad is our assumption of impulsive ? V application, and how does it affect the results? These are the questions that will be investigated in this chapter.
Specifically, the following topics will be considered: 1) N-impulse maneuver, 2) fixed-impulse transfers, 3) finite-duration burns, and 4) very low thrust transfers.
In previous chapters, we have seen cases in which a two-impulse maneuver can accomplish the same transfer as a single-impulse but at a considerable ? V saving (e.g., argument of perigee change). Similarly, cases were studied in which a three-impulse maneuver was best (e.g., bi-elliptic transfers). The obvious next question is: What about four or more impulses?
Edelbaum [1] has answered this question exactly in his paper "How Many Impulses?" The answer, he finds, is that only in rare situations are more than three impulses required to obtain the minimum ? V transfer.
[1]Edelbaum, T. N., "How Many Impulses?," Aeronautics and Astronautics, Nov. 1967.
To date, nearly all of the satellites that have been placed in low Earth orbit by the Space Shuttle have achieved their final mission orbit using solid-propellant rocket motors. Whether...
