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

Abstract

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 criticality 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. Nomenclature COD ij= criticality of dependency between node i and node j COD_O j = part of the operability of node j depending on the criticality of all its dependencies COD_O ji = part of the operability of node j depending on the criticality of the dependencies from node j O i = operability of node i SE i = self-effectiveness of node i SOD ij = strength of dependency between node i and node j SOD_O j = part of the operability of node j depending on the strength of all its dependencies SOD_O ji = part of the operability of node j depending on the strength of the dependencies from node j

Equipment Mission Safety Evaluation Method Based on Function-Structure

“…Besides its timeliness and health, the edges attribute also include the Strength of Dependency [15,34,35] (SOD) and the Criticality of Dependency [15,34,35] (COD). Among them, SOD refers to the degree of contribution to the node's SOL, and COD refers to the degree of restriction to the node's SOL.…”

“…The BSOL of the node in the safety structure layer is determined by the main technical and tactical indexes of the node.CSOL indicates the SOL of a node at the current moment, and is determined by the dependency relationship. It is supposed that all nodes can run independently and exert their capabilities relying on BSOL[34,35], but may not be able to complete the roles and functions that they should play in the system. Most nodes need to exert their normal safety operating capability, mainly relying on the SOL of the nodes that control them.In addition, the completion of function needs the support of the nodes (software, hardware) in the safety structure layer.…”

Deriving Global Criticality Conditions from Local Dependencies Using Functional Dependency Network Analysis (FDNA)

“…A case study by Garvey, Pinto, and Santos [] describes relationships between FDNA and I‐O approaches. Recently, FDNA has been applied to isolating operationally critical nodes and elements in the design and architecture of complex spacecraft systems and systems of systems [Guariniello and DeLaurentis, , ].…”

Analyzing Ballistic Missile Defense System Effectiveness Based on Functional Dependency Network Analysis

“…FDNA has been applied in the SoS analysis for wide domains. Guariniello extended FDNA in both operational and development networks to analyse the complex dependencies between the systems and capabilities of SoS, applied in the aerospace SoS design and architecture [10]. Drabble [11] applied the dependency network analysis to identify the key dependent nodes and conduits within the information propagation network for emergency response.…”

“…Wang [12] and Zhang [13] analyzed the SoS security of Global Navigation Satellite Systems (GNSS) based on FDNA technique. Accordingly [9,10], in the FDN, the nodes represent systems or capabilities, while the links represent the operational dependencies between the systems or between the capabilities. Each dependency is characterized by strength (Strength of Dependency, SoD) and criticality (Criticality of Dependency, CoD), that affect the behavior of the whole SoS in different ways.…”