Increasing the Node Shifting Capability of Fixed Velocity Upper Stage Payloads Using Slightly Elliptic Drift Orbits

For geosynchronous mission scenarios, noticeable increases in node shift can be made by allowing the drift orbit to be slightly elliptic while keeping the semimajor axis the same. By performing the apogee motor burn at the elliptic drift orbit apogee altitude, the required orbit insertion velocity is less than that required for a circular orbit. Thus, the excess velocity gained can then be utilized for additional node shift. Since the launch window duration of a fixed-velocity payload is a direct function of the node shift capability, any increase in node shift performance will also increase the available launch window.

This paper presents a fundamental understanding of the effects of drift orbit eccentricity by examining the drift rate, specific mechanical energy and angular momentum, circularization velocities, node shift capability, argument of perigee, and launch window duration.