A Superconducting Gravity Gradiometer for inertial navigation

A sensitive gravity gradiometer suitable for operation on an aircraft or ship is being constructed. The design is based on superconducting accelerometer technology developed at the University of Maryland over the past two decades. A cryogenic instrument not only benefits from reduced thermal noise, but more importantly from the extraordinary stability of superconducting circuits and material properties at near-zero temperatures. The latter permits precise matching of scale factors and accurate rejection of dynamic errors. One of the main perceived drawbacks of the Superconducting Gravity Gradiometer (SGG) has been the necessity for a liquid helium cryostat. To avoid this constraint, the SGG is being integrated with a closed-cycle refrigerator for operation at 3 K.