TORC-SP: High Torque, Low Jitter Scissored-Pair CMG Technology

NASA sees an increasing role in the near future for small satellites in the 5-100 kg size range. A potentially disruptive technology, small satellites are being eyed as platforms for the rapid demonstration of new technologies and important science missions. Currently, small satellite platforms struggle to balance the three critical tasks of (1) collecting enough power, (2) acquiring data and (3) downlinking that data to ground stations in a way that maximizes mission return. For these small platforms, which usually do not benefit from steer-able solar arrays or gimbaled antennas and instruments, optimally balancing these three tasks strongly depends on the satellite's attitude control agility. Spacecraft agility has to do with rapid retargeting, fast transient settling and low jitter pointing control. Dr. Bong Wie, renowned spacecraft attitude control expert and Professor of Aerospace Engineering at the Iowa State University, has stated that ultimately the "measure of an agile satellite attitude control system is its ability to collect the maximum data from an area on the Earth that is rich in data-collection opportunities". A logical corollary following from this statement would be that to maximize satellite data-collection, system designers should look to increase the satellite's agility. Furthermore, in addition to data-collection, the other two critical tasks of power collection and data downlink are also maximized as agility is increased. Honeybee Robotics proposes to develop a low cost, high torque and low jitter satellite attitude control actuator derived from its Tiny Operationally Responsive CMG (TORC) design. This derivative product would combine two TORC units into a single scissored-pair configuration with SPA compatible interface. The result, TORC-SP, would be an actuator with the simple control interface of a reaction wheel that offers 1-2 orders of magnitude more torque per unit mass at drastically less power than a reaction wheel.