This is the resonator for a Hemispherical Resonator Gyro (HRG). An HRG senses acceleration by the change in phase of vibration of a cup-shaped resonator, similar to the way a wine-glass resonates when rubbed by a wet finger. The device is rugged and accurate, and it has replaced other models of mechanical gyroscopes on most deep-space missions, as well as in other applications.
Northrop Grumman donated this to the Museum in 2011.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.