A method and system for satellite control in space using an IP-based satellite bus and all-IP compliant subsystems and payload(s) and a corresponding T&C system. Specifically, the present method/system includes a satellite-based IP Bus (connected as a network) that relies on Ethernet, USB, WIFI, or Bluetooth to connect various satellite components, satellite components configured to communicate on the IP bus, and a T&C system that understands the IP bus and can read its telemetry and commands. The system permits operations control on-orbit, in near real time within a secure system environment, with a dramatic increase in mission efficiency, an expansion of how much and what can be done on-orbit, and cost savings on future missions using IP-compliant spacecraft and payloads.

The present disclosure provides a system and a method for controlling a motion of a spacecraft in a multi-object celestial system while avoiding an unauthorized entry into a keep-away region during a normal and an abnormal operation of the spacecraft. The method includes executing, during the normal operation of the spacecraft, a nominal control law subject to constraints on maintaining a state of the spacecraft within a union of a plurality of control invariant sets of values of the state of the spacecraft. The state of the spacecraft includes a location of the spacecraft and at least one or a combination of a velocity and an acceleration of the spacecraft. The method further includes executing, upon detecting the abnormal operation of the spacecraft, an abort control law associated with the control invariant set including a current state of the spacecraft.

An attitude control system includes one or more control moment gyro pairs, with gyros of individual of the pairs being counter-rotated to rotate the rotation axes of flywheels of the gyros of a gyro pair in opposite direction. The flywheels of a gyro pair may be in paddle configuration, with the rotation axes of the flywheels rotating in the counter-rotation through separate planes as the gyros are rotated. The rotation of the gyros of a gyro pair may be accomplished by coupling both of the gyros to a servo motor with suitable coupling gears, or by using independent servos for each gyro. The counter-rotation of gyros of an individual pair produces a resultant torque about a fixed global axis, such as the axis of a flight vehicle of which the attitude control system is a part. Further control may be accomplished for example by varying rotation speeds of the flywheels.

A three-loop inertial stabilization system with active jitter suppression and optical control to reduce line-of-sight (LOS) jitter based on platform induced motion in cantilevered gimbal systems. A first loop comprises at least one rate sensor, a Kalman state estimator, and a rate to angle module. A second loop comprises a mirror system, a focal plane and centroid processing module, an open-loop closed loop selector, a signal combiner and a loop integrator. A third loop comprises a fast steering mirror, offload module and at least one gimbal motor driver, wherein the three loops suppress the jitter of the cantilevered gimbal system.

A lunar orbiting satellite system executes orbit planning of assigning a function (positioning, communication, and flashing) to an artificial satellite (AS) depending on a relative position of the AS to the moon at a time when the moon and the AS are observed from an input point on the earth, and correcting the relative position, which changes in accordance with the moon revolution period. The system includes: a satellite orbit planner which assigns a function to each ASs forming an AS group flying around the moon depending on a relative position of each ASs to the moon at a time when the moon and ASs are observed from an input point on the earth, and set a target orbit according to the function; and a satellite controller which causes the each ASs to execute control based on the function to implement switching of the function.

The present invention provides a method for refined attitude control based on output feedback for a flexible spacecraft. The control method comprises the following steps of: a) building a flexible spacecraft dynamical system Σ.sub.1, converting the flexible spacecraft dynamical system Σ.sub.1 into a flexible spacecraft dynamical system Σ.sub.2, and incorporating spacecraft rigid-flexible coupling dynamic disturbance into the flexible spacecraft dynamical system Σ.sub.2; b) constructing an external system Σ.sub.3, and describing the rigid-flexible coupling dynamic disturbance through the external system Σ.sub.3; c) configuring a disturbance observer for estimating the value of the rigid-flexible coupling dynamic disturbance; d) configuring a dynamic output feedback H.sub.∞ controller; e) compounding the disturbance observer in step c) with the dynamic output feedback H.sub.∞ controller in step d) to obtain a flexible spacecraft refined attitude control system Σ.sub.6; the flexible spacecraft refined attitude control system Σ.sub.6 compensating for the rigid-flexible coupling dynamic disturbance through the estimated value.

A new approach for rapid slew and settle of small satellites is based on four single degree-of-freedom control moment gyroscopes with variable speed flywheels (or reaction wheels) in a pyramid configuration, combined with path and endpoint constraint time-optimal control. The path and endpoint constrained time-optimal control can be augmented with momentum management without the use of additional actuators.

A satellite in orbit around a planetary body includes a bus and a drag flap coupled to the bus. The drag flap is used to increase the drag torque applied to the satellite. The bus may house sensors and actuators, such as a star tracker, a gyroscope, a reaction wheel, and a global position system (GPS) receiver to monitor the attitude of the satellite in response to the applied drag torque. The measurements from the sensors and actuators may be used to determine the drag torque applied to the satellite. An estimate of the atmospheric density may be then be determined based on the drag torque. Compared to conventional approaches, the satellite and methods described herein estimates the atmospheric density at comparable, if not better, resolution and bandwidth. The atmospheric density estimates may also be acquired in real-time using a cheaper, lighter, and smaller satellite.

Apparatus and methods for controlling a spacecraft for a transfer orbit. The spacecraft includes a momentum subsystem that stores angular momentum relative to a center of mass of the spacecraft, and a propulsion subsystem that includes electric thrusters. A controller identifies a target spin axis for the spacecraft, determines gimbal angles for electric thruster(s) that so that thrust forces from the electric thrusters are parallel to the target spin axis, and initiates a burn of the electric thruster(s) at the gimbal angles. The controller controls the momentum subsystem to compensate for a thruster torque produced by the burn of the electric thrusters. The momentum subsystem is able to produce a target angular momentum about the center of mass, where a coupling between the target angular momentum and an angular velocity of the spacecraft creates an offset torque to counteract the thruster torque.

A method for attitude control of a satellite in inclined low orbit in survival mode is disclosed, the satellite including at least one solar generator, at least one solar sensor, magnetic torquers capable of forming internal magnetic moments in a satellite reference frame having three orthogonal axes X, Y, and Z, and inertial actuators capable of forming internal angular momentums in the satellite reference frame. The at least one solar sensor has a field of view at least 180° wide within the XZ plane around the Z axis, the method including a step of attitude control using a first control law, a step of searching for the sun by means of the at least one solar sensor, when a first phase of visibility of the sun is detected, and a step of attitude control using a second control law.