Control of the ST7 Disturbance Reduction System Flight Experiment

The Space Technology 7 (ST7) experiment will perform an on‐orbit system‐level validation of two specific Disturbance Reduction System technologies: colloidal micronewton thrusters and drag‐free control. The ST7 Disturbance Reduction System (DRS) is designed to maintain the spacecraft’s position with respect to a free‐floating test mass while limiting the residual accelerations of that test mass over the frequency range of 1 to 30 mHz. This paper presents the overall design and analysis of the spacecraft drag‐free and attitude controllers, with particular attention given to its primary mission mode. These controllers close the loop between the drag‐free sensors and the colloidal micronewton thrusters.