Mission-Optimized Waiting Orbits and Transfer Trajectories for GEO Target Rendezvous

It is becoming increasingly necessary for orbiting mission vehicles to rendezvous with target satellites in or near geosynchronous equatorial orbit (GEO), for example to perform on-orbit inspection, servicing, or refueling, or for various types of military proximity operations. The rendezvous of the mission vehicle with the target often must be initiated on short notice and achieved quickly. The total rendezvous time and the propellant consumed in performing the rendezvous are the two main considerations in choosing an optimal waiting orbit and transfer trajectory for the mission vehicle. Propellant-efficient transfer options include a Hohmann transfer or bi-elliptic transfer, though faster but less efficient transfers can also be considered. The waiting orbit for the mission vehicle can be chosen anywhere from LEO to GEO, though waiting orbits above GEO can also be considered, and both prograde and retrograde orbits can be considered. The chosen waiting orbit determines the time between successive rendezvous opportunities and the required orbit transfer time, as well as the amount of propellant needed to perform the rendezvous. The relative importance assigned to reducing propellant consumption versus reducing the rendezvous time depends on the mission. Therefore, this project conducts an in-depth Keplerian analysis of such mission-optimized waiting orbits and transfer trajectories for GEO target rendezvous, and will determine the optimal configuration for any given relative emphasis on reducing the rendezvous time versus reducing propellant consumption.