Toward a Dynamically Reconfigurable Computing and Communication System for Small Spacecraft

Future science missions will require the use of multiple spacecraft with multiple sensor nodes autonomously responding and adapting to a dynamically changing space environment. The acquisition of random scientific events will require rapidly changing network topologies, distributed processing power, and a dynamic resource management strategy. Optimum utilization and configuration of spacecraft communications and navigation resources will be critical in meeting the demand of these stringent mission requirements. There are two important trends to follow with respect to NASA’s (National Aeronautics and Space Administration) future scientific missions: the use of multiple satellite systems; and the development of an integrated space communications network. Reconfigurable computing and communication systems may enable versatile adaptation of a spacecraft system’s resources by dynamic allocation of the processor hardware to perform new operations or to maintain functionality due to malfunctions or hardware faults. Advancements in FPGA (Field Programmable Gate Array) technology make it possible to incorporate major communication and network functionalities in FPGA chips and provide the basis for a dynamically reconfigurable communication system. Advantages of higher computation speeds and accuracy are envisioned with tremendous hardware flexibility to ensure maximum survivability of future science mission spacecraft. This paper discusses the requirements, enabling technologies and challenges associated with dynamically reconfigurable space communications systems. Background Communication system architectures with multiple small spacecraft are being planned to realize the science required for future NASA missions. This emerging trend of multiple spacecraft architecture holds advantages over a single large spacecraft because of its distributive processing nature, and the adaptability of the system to meet the evolving needs of the missions. Large, single-spacecraft systems (such as Hubble Space Telescope) have nearly reached the fundamental limit in image resolution attainable by such systems, and thus new architectures have to be created to meet the demands of future science missions. Using collaboration of multiple spacecraft enables greater resolution, improves remote sensing performance, and provides robustness over current implementations [1]. The future architectures of multi-spacecraft systems can be classified into a number of configurations [2, 3]: • Well-defined constellations of nodes orbiting a celestial body like Earth or Mars forming a network of sensors with inter-satellite links and/or relay communications hubs. • Fixed formation flyers of cooperating nodes, configurable in fixed symmetrical geometries; free flying nodes (or self-organizing sensor nodes) that organize to observe and measure events in real time. • Ultra small free flying sensor nodes that form ad-hoc networks for monitoring events. Reconfiguring the cluster geometry will allow multiple mission sets to be performed. Figure 1 depicts various multiple spacecraft systems and their configurations. NASA/TM—2003-212348 1Muli Kifle, Monty Andro, Quang K. Tran, and Gene Fujikawa National Aeronautics and Space Administration Glenn Research Center Cleveland, Ohio 44135 Pong P. Chu Cleveland State University Cleveland, Ohio 44115