A micromachined earth sensor based on measuring the gravity gradient torque

We present the fabrication and testing of a novel MEMS inertial sensor that directly measures the gravity gradient in low Earth orbit in order to sense the relative orientation of a satellite with respect to the Earth. Instead of the current Earth sensing methods that determine the Earth vector by sensing the Earth’s IR emission, we present a much lighter and more compact MEMS-based approach that determine the Earth vector by measuring the Gravity Gradient Torque on an elongated silicon proof mass. Current Earth sensors require optical access on multiple faces of the satellite. This MEMS-based approach does not require optical access.