At the Air Force Research Laboratory's Space Vehicles Directorate we are investigating and developing architectures for commanding and controlling a cluster of cooperating satellites through prototype development for the TechSat-21 program. The objective of this paper is to describe a distributed satellite testbed that is currently under development and to summarize near term prototypes being implemented for cluster command and control. To design, develop, and test our architecture we are using eight PowerPC750 VME-based single board computers, representing eight satellites. Each of these computers is hosting the OSE/sup TM/ real-time operating system from Enea Systems. At the core of our on-board cluster manager is ObjectAgent. ObjectAgent is an agent-based object-oriented framework for flight systems which is particularly suitable for distributed applications. In order to handle communication with the ground as well as to assist with cluster management, we use the Spacecraft Command Language (SCL). SCL is also at the centerpiece of our ground control station and handles cluster commanding, telemetry decommutation, state-of-health monitoring, and Fault Detection, Isolation, and Resolution (FDIR). For planning and scheduling activities we are currently using ASPEN from NASA/JPL. This paper describes each of the above components in detail and then presents the prototypes being implemented.
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