In the past decade, CubeSats have started a new chapter in space exploration and research. CubeSats present university students with a unique opportunity to gain hands-on experience in designing and flying satellites. Advancements in technology have allowed more powerful electronics to fit within the CubeSat constraints and launch providers are willing to launch these spacecraft as secondary payloads. With new advancements in technology and flight heritage, CubeSats are becoming a valuable research tool for NASA, the NSF, and many other institutions. Beyond the standard size, mass, and testing requirements, there are few similarities between CubeSats developed at different institutions; the structures are often uniquely designed and the software is written to be functional for the current mission. Now, as small satellites become more accepted and useful to the scientific community, there is an increased need to create a reusable and modular satellite support bus for a third party payload. Science customers can develop their own instruments, integrate into a working satellite through simple software and hardware interfaces, and gain access to space. This thesis is focused on the research conducted for the University of Texas at Austin Satellite Design Laboratory’s current ARMADILLO and Bevo-2 CubeSat projects. Though the missions for these two satellites are very different, both satellites benefit from the same research around a common hardware and software bus design. Both the structure and software research is inspired by modularity. Hardware is grouped into modules and included within a ‘wall shell’. All of the modules, including a designated payload module, are easily connected by ‘section connectors’ to create a functioning satellite. The flight software ‘Hookem’ also creates modules of code for each subsystem. This ‘Interface Object Software’ gives the Command and Data Handling subsystem full access to the subsystem software functions the satellite can execute in its mission. Both the structure and software modules can be changed out as hardware or mission objectives change for future projects or to support a payload. The Satellite Design Laboratory has a rich history in designing, building, and operating small satellites. Because the lifespan of small satellite projects are only a few years, the Lab has recognized the challenges of transferring knowledge and work between missions. The target of this research is to create a modular and reusable bus design that reduces the non-recurring engineering time and costs of starting new satellite projects. With careful future planning, the structure and software for a small satellite bus can be designed and developed to benefit future missions. The ultimate goal is to create a capable satellite to support nearly any customer’s needs.