The innovation is to embed a MEMS IMU Sensor Chip into a reaction wheel to measure its spin rate as well as wheel attitude rate. We propose to use a reaction wheel such as the NASA Goddard reaction/momentum wheel (SMEX) because of its high degree of development and capability for static and dynamic balancing. The IMU Sensor Chip will derive stability from the inertia of the wheel resulting in greater precision and accuracy. During Phase I we propose to integrate the two entities and test the operation of the MEMS gyroscopes and accelerometers of the IMU Sensor Chip to demonstrate the benefits of the union. In addition to attitude sense and control, the combination would also improve GN&C and enable autonomous operation in GPS-denied environments.