We begin to see an increase in the diversity of today's space missions: Small studentdesigned satellites, unique scientific missions and fleets of commercial spacecraft are just a few of those mission types. In order to cater for new demands on the ground system and to offer customer-tailored solutions we started to rethink the foundations of the German Space Operations Center (GSOC) ground system in terms of a service-oriented architecture approach using standardized technology, mainly CCSDS Mission Operations services. We show how we modularize our ground system, identify and clearly name the mission functions present in the current system complete with timing information and data size requirements. We illustrate this process by employing a concrete prototypical mission with involvement across all departments from antenna control, data processing to mission planning and flight dynamics, and hint at the challenges encountered along the way. The chosen technical solution is motivated and explained, and aspects of deployment, performance, and security are discussed. Nomenclature