Fault Tolerant Architecture Design of a CubeSat Command and Data Handling System

In recent years CubeSat satellite missions have been covering an increasing number of applications with a relatively low-cost budget. In this context, most CubeSat missions use COTS components. Therefore a variety of fault tolerance techniques must be used to obtain the required dependability. This work presents the design methodology that is being followed by the authors in the design of a command and data handling subsystem (C&DH) for CubeSats. The final design of this proposed C&DH subsystem will be included as a secondary payload in the Latin American Satellite Mission, a 3U CubeSat remote sensing mission that will acquire Earth's surface images for use in forestry and agricultural analysis. At the time of writing this paper, a C&DH preliminary version is complete, and a set of fault injection experiments are under development with the goal of identifying and fixing weaknesses in the fault tolerance mechanisms. A review and analysis of C&DH subsystems in recent commer-cial and academic CubeSat projects are presented. As a result of this analysis, a master-supervisor architecture was adopted. The method for estimating the expected rate of SEU and SEFI radiation effects in the planned orbit of the Latin American Satellite Mission is presented, and the adopted master-supervisor architecture is detailed. Finally, a brief description of the planned fault injection experiments is presented.