Advantages of tether release of satellites from elliptic orbits

This paper examines the use of an elliptically orbiting tethered-dumbbell (Space Shuttle-satellite) system for satellite transfer to geosynchronous altitude. The two-dimensional rigid-body equations of motion are derived using a Lagrangian method. Integration of these equations yields the system states, from tether deployment through payload release. The payload is given a “forward swing zero libration” release, i.e., the payload is released on a forward swing when the libration angle is instantaneously zero. By varying the predeployment true anomaly, the “forward swing zero libration” is caused to occur nearly simultaneously with periapse passage, yielding maximum savings in ΔV in comparison to Hohmann-type transfer from the same elliptic orbit to geosynchronous orbit. Deployment velocity and tether length were also varied so that their effect on ΔV savings could be determined. The maximum ΔV savings observed was 9%, corresponding to a payload mass gain of almost 23%.