Absolute gravimeters that exhibit low long term drift are critical to monitoring the dynamics of Earth's gravitational field at long time scales. The Earth's gravitational field provides information on ocean dynamics, subterranean fluid flow including hydrology and the movment of magma and other fluids and plate techtonics. The most sensitive absolute gravimeters currently deployed are based either on macroscopic falling corner cubes that form one arm of a Michelson interferometer, or cold atom clouds in free fall. The intermediate regime, where the falling object is a microfabricated test mass is unexplored. In this project, in collaboration with researchers in electronic materials and engineering and with space instrumentation physicists, we will design, construct and test microfabricated gravimeters and gravity gradiometers that operate at the quantum noise limit.