Fabrication and testing of a MEMS based earth sensor

We present a novel MEMS inertial sensor that directly measures the gravity gradient in order to sense the relative orientation of a satellite with respect to the Earth. An Earth sensor provides an orbiting satellite with a vector towards the Earth center. Current Earth sensors use optical methods to determine the Earth vector by sensing the IR emission from the Earth. This requires optical access on multiple faces of the satellite. We present here the microfabrication and preliminary testing of a much lighter and more compact MEMS-based approach to determine the Earth vector by measuring the torque induced on an elongated body due to the gravity gradient.