Simple Optimization of Inclination changes for On-orbit Servicing at GEO

View Video Presentation: https://doi.org/10.2514/6.2023-0155.vid On-orbit servicing (OOS) is a promising development in space operations geared towards reducing launch costs, as well as the number of launches and volume of objects in orbit. Servicing operations offer the prospect of extending a satellite’s operational lifetime and therefore reducing the need to launch new satellites and further contributing to the problem of traffic in Earth orbit. This investigation seeks to add to the body of literature related to OOS by proposing a mission methodology for fleets of servicing vehicles. In this work it is proposed to have a fleet of servicing vehicles occupy different orbital inclinations around Earth at GEO. In this methodology, it is assumed servicing vehicles are to transfer from the original inclination to rendezvous with a satellite in need of servicing at a different inclination The focus of this research is to find the most fuel-efficient path to transfer a hypothetical refueling vehicle between orbital inclinations. Efficiency is determined by comparing many inclination changes between the range of 0° to 90°. All inclinations considered are for circular geosynchronous orbits (GEO) and the inclination changes are completed at varying multiples of GEO radius; only impulsive burns are modeled in this present paper. The actual rendezvous and method of servicing is not considered in this investigation. The initial results of this investigation indicate that as inclination changes become more extreme it becomes more fuel efficient to transfer to greater multiples of GEO. However, for smaller inclination changes it remains most efficient to remain at or close to GEO. This is because at smaller changes of inclination, the cost of the Hohmann transfer dominates the total maneuver cost. As the changes in inclination become greater and begin to dominate the overall costs, it becomes worthwhile to spend fuel to raise the orbit and save ∆v on the inclination change itself. The inflection points in ∆v cost appear to lie between the changes of 30° and 60°. The inflection points between the different multiples of GEO were then found. The results of this research indicate that when using the method of transfer proposed, as inclination changes become greater, it becomes more efficient to maneuver to a greater altitude to execute the inclination change. Of the altitudes investigated in this research, a point was not found in which greater inclination changes were not more efficient at some higher altitude. This appears to indicate that as the size of the inclination change grows, so too does the efficient altitude at which to execute that inclination change to minimize ∆v use. The results of this research provide a foundation for future work to develop a schema of efficient transfers between orbital planes for the purpose of OOS or other general space operations.