Abstract: A spacecraft control system having a spacecraft with a gimbaled thruster attached thereto. An actuator is operationally attached to the gimbaled thruster to control the angled position of the gimbaled thruster in two orthogonal directions. A position control system is provided which sends a control signal to the actuator which moves the gimbaled thruster to an angled position in response to the control signal, wherein the angled position of the gimbaled thruster controls the attitude and orbital velocity of the spacecraft.

Abstract: A method and system for supporting a test article or structure in a gravity environment for the purpose of testing the article in a simulated weightless condition includes at least one support assembly attached to the article for suspending the article from an overhead support. The support assembly includes three cables each having an end attached to the article. The cables are capable of being actuated to cooperatively maintain a constant resultant vertical force on the test article which is equal to the weight of the article. The system includes a controller which is capable of adjusting the force in each cable to continuously maintain the constant resultant force on the article as it moves from position to position. The controller can calculate the new position of the test article as it moves from position to position.