A performance support system (PSS) for a satellite systems crew, called the Adaptive Decision Enabling Performance Support Toolset (ADEPT), has been designed to promote performance and the continued development of operator expertise. Several characteristics of the satellite operator domain make designing a tool from this perspective particularly appropriate. For example, satellite systems crewmembers experience frequent periods of low activity and subject matter experts have indicated that better crewmembers tend to use that time to seek explanations about how the system works and how their tasks affect the system. ADEPT will support performance and foster the development of expertise by providing satellite systems crew with knowledge-based tools that offer explanation, guidance, and visualization. For example, it features a satellite visualization tool that crewmembers can use in real time to assess satellite positioning or that they can use during periods of low activity to improve their conceptualization of the remote system components they maintain. In addition, the satellite system for which this PSS is being developed is rapidly evolving. Thus, there is always more to learn, and a need to supplement formal training as it struggles to keep pace with the changes. This paper will discuss the design process and problem definition of ADEPT, outline the functions that support learning, and conclude with lessons learned from the design process and possible opportunities to generalize the concept of including learning support in a PSS.