A numerical optimization study of low-thrust orbital transfer will be considered. The problem will be to transfer a spacecraft between two earth orbits with the idea of performing a rendezvous of a chaser spacecraft with a target spacecraft. The problem will be modeled using the full nonlinear dynamics. Typical low-Earth orbits will be considered (for example, rendezvous with the International Space Station orbit from another low-Earth orbit). Both minimum-time and minimum-fuel transfers will be considered.