Energy efficient satellite maneuvering is described herein. One disclosed example method includes maneuvering a satellite that is in an orbit around a space body so that a principle sensitive axis of the satellite is oriented to an orbit frame plane to reduce gravity gradient torques acting upon the satellite. The orbit frame plane is based on an orbit frame vector.

A method controls an operation of a spacecraft according to a model of the spacecraft. The method determines control inputs for controlling concurrently thrusters of the spacecraft and momentum exchange devices of the spacecraft using an optimization of a cost function over a receding horizon subject to constraints on a pose of the spacecraft and constraints on inputs to the thrusters. The cost function includes components for controlling the pose of the spacecraft and a momentum stored by the momentum exchange devices. The method generates a command to control concurrently the thrusters and the momentum exchange devices according to at least a portion of the control inputs.

A method for controlling the orbit of a satellite in earth orbit. The orbit of the satellite is controlled by commanding, according to a maneuver plan, a propulsion system having at least one thruster and a transporter to move the propulsion system. The maneuver plan includes at least two orbit-control maneuvers. The thrust powers of the propulsion system during the two orbit control maneuvers have respective thrust directions that are not parallel in an inertial frame of reference. Each thrust power is determined to simultaneously control the inclination and the position of the orbit of the satellite as well as to form a momentum that is suitable for unloading a device for storing angular momentum of the satellite in a plane orthogonal to the direction of thrust of the thrust power.

Methods and apparatus to methods and apparatus for performing propulsion operations using electric propulsion system are disclosed. An example method includes deploying a space vehicle including an electric propulsion system; and using the electric propulsion system for attitude control and orbit control, no other propulsion system provided to enable the attitude control and the orbit control.

A method for controlling an attitude control system (30) for a space vehicle (10), the attitude of the space vehicle being controlled during at least one preparation phase followed by an observation phase during which an image capture is performed. In an attitude control system that includes a maneuvering subsystem (300) which includes at least one reaction wheel, the method includes, during the at least one preparation phase, a preparation step (50), during which commands are issued to the maneuvering subsystem in order to control the attitude of the space vehicle, followed by a step (55) of stopping the at least one reaction wheel prior to the observation phase. In addition, during the observation phase, a fine control subsystem (310) having a lower vibration signature than that of the maneuvering subsystem, is sent commands in order to control the space vehicle's attitude. An attitude control system for a space vehicle is also described.

An integrated Reaction Wheel Assembly Array (RWAA) includes a multi-rotor chassis having a plurality of bearing locating features. A plurality of rotor assemblies is mounted to the multi-rotor chassis. Each rotor assembly includes a rotor having a rotor shaft, a spin motor coupled to the rotor and configured to drive rotation of the rotor about a spin axis, and a first spin bearing assembly disposed around an end portion of the rotor shaft. The first spin bearing pilots to one of the bearing locating features to position or locate the spin axis of the rotor assembly in a predetermined fixed spatial relationship relative to the spin axes of the other rotor assemblies.

An improved spacecraft actuator wheel is provided which can be operated as a momentum wheel, a reaction wheel or a gimbal. The actuator wheel has a central cavity. One or more battery modules are located within the actuator wheel's central cavity. The battery modules supply power to one or more electronic components affixed to the actuator wheel or mounted on the spacecraft frame via an electrical harness. In addition, the actuator wheel's central cavity is pressurizeable for storing spacecraft propellant which can be controllably diverted to the spacecraft's thrusters through conduits and flow valves.

The disclosed subject matter relates to a reaction wheel system for controlling and stabilizing a satellite or other spacecraft. The reaction wheel system includes a reaction wheel rotor and a containment structure stator including a plurality of contactor assemblies for securing the reaction wheel rotor when not in rotation and for electromagnetically inducing substantially frictionless rotation of the reaction wheel rotor.

Provided is an apparatus for controlling an orbiting satellite by sensing a change in a yaw angle of the orbiting satellite and calculating a ground sample distance (GSD) based on the yaw angle. The apparatus may include a sensor configured to sense a yaw angle corresponding to yaw steering of the orbiting satellite, and a processor configured to calculate, based on the yaw angle, a GSD corresponding to a length of a pixel projected onto a planetary surface scanned by the orbiting satellite.

The invention relates to a drive arrangement containing a rotational mass which is supported so as to be rotatable about a first axis, a bearing element supported so as to be rotatable about a second axis extending perpendicular to the first axis having a bearing for supporting the rotational mass, an oscillating body supported so as to be rotatable about a third axis perpendicular to the second axis having a bearing for supporting the bearing element, a drive provided on the oscillating body for generating a rotary movement of the bearing element about the second axis, a housing having a bearing for supporting the oscillating body, and a brake fixed to the housing for braking the rotary movement of the oscillating body in such a way that with each braking operation a driving force is transmitted to the housing.