Distributed Satellite Systems
As NASA moves towards its goal of "faster, cheaper, better," space scientists and engineers are looking for ways to accomplish more in less time, with less money. As the paradigm shifts from one-of-a-kind, heavily instrumented large spacecraft to small, inexpensive spacecraft, it is becoming apparent that some space research needs are better met by a group of small satellites, rather than by a single large satellite. This is similar to what has happened over the past several decades in the computer industry, as the focus has changed from using large, expensive mainframes for solving computationally intensive problems to using smaller, cheaper, more adaptable sets of distributed workstations in collaboration. The goal of the program in Distributed Satellite Systems (DSS) is to identify spacecraft functions that can benefit from distribution, to characterize the issues associated with this approach, and to experimentally demonstrate how these issues may be addressed. This research will demonstrate how clusters or formations of smaller, cheaper spacecraft can achieve the same missions as current larger, more expensive, monolithic spacecraft with improved performance at lower cost.
To achieve this goal, the DSS program employs systems analysis and specialized dynamic modeling concurrently with experimental work. Satellite formations in low Earth orbit encounter perturbing gravitational forces due to deviations from spherical in the Earth's shape. MIT Space Systems Laboratory researchers are working on ways to linearize the models of these effects to allow more precise control of relative satellite positions in orbit.
Experimental work has focused on the DSS Testbed and the SPHERES Formation Flying Testbed. Research on the DSS Testbed demonstrated the ability to perform acoustic interferometry, and is now complete. The SPHERES testbed is intended for the development and validation of formation flying control algorithms and topologies, and is slated for a flight to the International Space Station in early 2003. You can see the SPHERES project home page for more information about this project.
