The command and control system will be a layer of systems software above the RTOS kernel that supports the specification of mission operations rules, constraints, sequences and high-level commands. This command and control layer should include an API (Application Programmer's Interface) such that it can be interfaced with sophisticated user interface, interprocess communication, data management, and automation software in the ground segment as well as with reusable device drivers, data management, fault detection, and communications software to be incorporated in the space segment. The rule-based command and control is key for providing a framework for evolving automation, and thus overall operational autonomy, toward higher and higher levels. Simple rules for sating in the onboard segment can be augmented with more "intelligent" rules to maximize performance and minimize human operational attention required as a mission progresses and over a range of related missions. Careful design of such systems to enable them to be embedded and to be distributed is required, but this has been done successfully [8,14].