The objective of this report is to discover a skyhook’s ability to change the plane of another spacecraft’s orbit while ensuring that each vehicle’s orbital energy remains constant. Skyhooks are a proposed momentum exchange device in which a tether is attached to a counterweight at one end and at the other, a capturing device intended to intercept rendezvousing spacecraft. Trigonometric velocity vector relations, along with objective comparisons to traditionally proposed uses for skyhooks and gravity-assist maneuvers were responsible for the ultimate parameterization of the proposed energy neutral maneuver. From this methodology, it was determined that a spacecraft’s initial relative velocity vector must be perpendicular to, and rotated about the skyhook’s total velocity vector if it is to benefit from an energy neutral plane change maneuver. A quaternion was used to model the rotation of the incoming spacecraft’s relative velocity vector. The potential post-maneuver spacecraft orbits vary in their inclinations depending on the ratio between the skyhook and spacecraft’s total velocities at the point of rendezvous as defined by the parameter called the alpha criterion. For many cases, the proposed maneuver will serve as a desirable alternative to currently practiced propulsive plane change methods because it does not costly require a substantial amount of propellant. The proposed maneuver is also more accessible than alternative methods that involve gravity-assist and aerodynamic forces. Additionally, by avoiding orbital degradation through the achievement of unchanging total orbital energy, the skyhook will be able to continually and self-sustainably provide plane changes to any spacecraft that belong to orbits that abide by the identified parameters.

The potential threat of Near Earth Objects (NEOs) and the need for effective planetary defense strategies has become increasingly urgent. While a range of mitigation techniques exist, the development of a space elevator could provide significant advantages in planetary defense. The current mitigation strategies require the use of a rocket in order to intercept the NEOs, and therefore launch lighter interceptors at lower velocities. However, the implementation of a space elevator would allow releasing heavier interceptors at much higher velocities. These capabilities combined with faster response times, make space elevators a much more efficient response to planetary defense. By using computational simulations on MATLAB to calculate intercept trajectories and model the new orbit of the NEOs after impact, this paper demonstrates that the use of space elevators can significantly improve the current strategies for planetary defense.