Designing Reusable Mission Operations Center Software Components: The Dependency Inversion Principle Applied to Satellite Command and Control

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) Ground Applications Group (SIG) develops Mission Operations Center software systems for all satellite missions supported by the JHU/APL Space Department. For efficiency, SIG designs these ground software systems to maximize reuse of existing software components, components include Commercial Off-The-Shelf satellite command and control products, Government Off-The-Shelf software, Open Source Software, and JHU/APL custom libraries and applications from previous missions. SIG has collected and successfully reused existing software components for over a decade, but experience has shown that coupling among the components can make reuse difficult. This paper presents a case study illustrating how the Dependency Inversion Principle can be applied to ground software component design to make it easier to reuse components in the future.