A reusable command and data handling system for university cubesat missions

A Command and Data Handling (C&DH) system is being developed as part of a series of CubeSat missions being built at the University of Texas at Austin Texas Spacecraft Laboratory (TSL). With concurrent development of four missions and with more missions planned for the future, the C&DH team is developing a system architecture that can support a variety of mission requirements. The presented research aims to establish a reference for the development of the C&DH system architecture so that it can be reused for future university missions. The C&DH system is designed using a centralized architecture with one main flight computer controlling the actions and the state of the satellite. A commercial off-the-shelf system-onmodule embedded computer running a Linux environment hosted on an interface board designed in-house is used as the platform for the mission software. An integral component of the C&DH system development is the flight software (FSW). The FSW is written in C++ using the Object-oriented architectural style. It is structured as a state machine, controlling the transitioning of the satellite between its operational modes which define its actions and behaviour. The various testing procedures that are performed on the FSW, the C&DH system and the integrated satellite are described. These procedures include traditional software tests such as black box, glass box, and unit testing, as well as formal spacecraft tests such as Command Execution Tests and Day-in-the-Life tests. The design of the flight software and the associated hardware are integral components of the current missions in the TSL which, when flown, will be some of the most operationally complex CubeSat missions attempted to date.