Agile Development of sub-CubeSat Spacecraft

Over 300 spacecraft weighing less than a kilogram have been launched to date, enabling low-cost satellite or constellation missions. These sub-CubeSat spacecraft have significantly reduced technical requirements and complexity compared to their larger counterparts, such as CubeSats, which are expected to lead to substantial cost benefits and development durations of one year or less. However, the median development time of sub-CubeSat spacecraft so far is more than two years, which can be explained by the lack of an adequate systems engineering framework to aid in managing their unique characteristics. In this article, we present a tailored methodology for sub-CubeSat spacecraft, which aims to reduce their development time and cost, consisting of specific methods, tools, and an Agile development process. This process focuses on Scrum- like short design sprints over the entire satellite system, followed by efficient verification and iteration, in contrast to the typical stage-gate processes of space systems engineering. Two internal space missions as case studies are used to demonstrate that our approach can decrease time-to-orbit and increase confidence in the design, by allowing quick adaptation to imposed constraints, evolving requirements, and unforeseen events.