Single, Hybrid, and Multimode Propulsion for On-Orbit Servicing

This study compared the mission performance of four propulsion system options (chemical, electric, hybrid chemical–electric, and single-propellant multimode design) applied to on-orbit servicing vehicles with masses of 100 kg in low Earth orbit (LEO) and 1000 kg in geosynchronous Earth orbit (GEO). First-order sizing routines were developed for each option, drawing on historical data, propulsion system properties, and standard mass allocations. The General Mission Analysis Tool was then used to simulate discrete maneuvers common to on-orbit servicing missions, such as orbit raising, phasing, and disposal, in both LEO and GEO environments. The results were assessed in terms of propellant use and maneuver time. These maneuvers were subsequently combined into representative mission scenarios, highlighting tradeoffs among the four propulsion architectures. The results show that, although chemical and electric single-mode systems excel in one operational dimension (fast transfers and high propellant efficiency, respectively), they lack flexibility for scenarios demanding both rapid response and propellant conservation. On the other hand, hybrid and multimode architectures meet broader operational demands, with multimode servicers providing a [Formula: see text] range four to ten times greater than hybrid propulsion ([Formula: see text] vs [Formula: see text] in LEO and [Formula: see text] vs [Formula: see text] in GEO).