The Subsystemless Satellite - A New Design Paradigm for the Next Generation of Small Satellites

Traditional satellite design techniques appear to break down for very small spacecraft weighing less than about 50 lbs. In order to break this barrier, it is necessary to implement a new satellite design paradigm - that of the "subsystemless" satellite. In such a satellite, the design process emphasizes the identification and specification of functional requirements per the usual systems engineering procedures. However, the identified requirements are never allocated to subsystems. Instead, the various spacecraft functions are implemented directly without regard to traditional spacecraft subsystem boundaries. The result is a highly integrated design which is compact, lightweight, and highly efficient. This approach also facilitates highly modular spacecraft designs because of the ease of implementing clean interfaces. This paper presents the results of a Government-funded study to develop a top-level design for a 15-lb nanosatellite to perform an actual operational mission. This nanosatellite is used as a case study to explore the characteristics and relative benefits of the "subsystemless" design paradigm, with emphasis on the design methodology employed.