  This paper proposes an on-orbit servicing logistics optimization framework
that is capable of performing the short-term operational scheduling and
long-term strategic planning of sustainable servicing infrastructures that
involve high-thrust, low-thrust, and/or multimodal servicers supported by
orbital depots. The proposed framework generalizes the state-of-the-art
on-orbit servicing logistics optimization method by incorporating user-defined
trajectory models and optimizing the logistics operations with the propulsion
technology and trajectory tradeoff in consideration. Mixed-Integer Linear
Programming is leveraged to find the optimal operations of the servicers over a
given period, while the Rolling Horizon approach is used to consider a long
time horizon accounting for the uncertainties in service demand. Several
analyses are carried out to demonstrate the value of the proposed framework in
automatically trading off the high- and low-thrust propulsion systems for both
short-term operational scheduling and long-term strategic planning of on-orbit
servicing infrastructures.
