The attitude and translation control system described in this paper provides precision pointing and drag-free control to accomplish a scientific mission. The unique proportional helium thruster, which uses helium boiloff from the payload, controls thrust using pressure feedback to meet the high-accuracy requirements for force knowledge. The attitude control law torque commands are combined with the translation control law force commands through a distribution matrix to determine individual thruster commands. The Global Positioning System (GPS) is used to determine position and velocity.