Maintenance and Recycling in Space: Functional Dependency Analysis of On-Orbit Servicing Satellites Team for Modular Spacecraft

This paper introduces an innovative perspective in the problem of on-orbit servicing and maintenance. A network of modular satellites and servicing satellites is modeled as a two-level System-of-Systems. At the lower level, the architecture of the modular satellites is analyzed in terms of functional interdepencies between the component modules. Analysis of the impact of such interdependencies gives insight into the operability of the satellite, and accounts for partial failures, redundancies, and cri ticality of the modules. At the higher level, communication, observation, and experimental satellites and constellation are constituents of a System-of-Systems functional network. The other components of this network are servicing satellites, able to perform inspection, refueling, maintenance. At this level, results from the overall functional dependency analysis are used to evaluate and compare different architectures, i.e. different number, capabilities, and location of servicing satellites. We discuss the innovation brought by the proposed approach with respect to the current practice. A hypothetical scenario is considered, featuring satellites with different architectures, whose parts are susceptible to aging and to failures over time, and on-orbit servicing satellites. Results show not only the general applicability of the method in order to perform analysis, but also possible future applications of both the proposed concepts and the analytical tool in space systems architecture and design.