Navigation with light refraction or dispersion and landmark data is provided. A system can include a data processing system. The data processing system can receive a first image of a surface of a planet from a first camera. The data processing system can generate a first position dataset based on the first image and data representing landmarks of the surface of the planet. The data processing system can receive, by a second camera oriented towards an atmosphere of the planet, a second image. The data processing can generate, via a celestial body catalog, a second position dataset based at least in part on an amount of refraction or dispersion of light of a celestial body in a second image. The data processing system can determine, based on a filter applied to the first position dataset and the second position dataset, a position and attitude of a vehicle.

The present invention provides a method for disturbance compensation based on a sliding mode disturbance observer for a spacecraft with a large flexible appendage, comprising steps of: a) building a spacecraft attitude control system; b) constructing an external system, the external system being incorporated with an uncertain portion of a damping matrix of a flexible appendage of the spacecraft; the external system being incorporated with an uncertain portion of a rigidity matrix of the flexible appendage of the spacecraft and describing a sum of flexible vibration and environmental disturbance; c) configuring a sliding mode disturbance observer for estimating the value of the sum of flexible vibration and environmental disturbance; d) compounding a nominal controller with the sliding mode disturbance observer in step c) to obtain a compound controller; the compound controller compensating for the sum of flexible vibration and environmental disturbance.

Provided is a method of comparing satellite attitude control performances, the method including generating, by a controller, a satellite task execution command, receiving, by an input and output (I/O) unit, a result of a simulation performed on a satellite attitude control by a satellite attitude control simulator based on the satellite task execution command, and transmitting, by the I/O unit, the satellite task execution command to a satellite based on the result of the simulation.

A method and system for anti-interference compound on-line guidance in the atmosphere-entering stage of a Mars lander is provided in the present invention. The method comprises steps of a) building a dynamics model for the atmosphere-entering phase of a Mars lander to incorporating the disturbance brought by the Mars atmosphere density uncertainty into the dynamics model for the atmosphere-entering stage of the Mars lander; b) constructing a disturbance observer to estimate the disturbance brought by the Mars atmosphere density uncertainty in the dynamics model for the atmosphere-entering phase of the Mars lander; c) building a prediction-correction guidance law, and guiding the heeling angle amplitude of the prediction-correction guidance law by continuously updating undetermined parameters; d) constructing an anti-disturbance composite guidance law to compensate the Mars atmosphere density uncertainty; and e) adjusting the deviation of the landing point of the Mars lander by compensating the Mars atmosphere uncertainty disturbance.

The present invention provides a method for attitude control based on finite time friction estimation for a flexible spacecraft. The control method includes the following steps: a. introducing spacecraft flywheel friction disturbance into a spacecraft dynamics system, and establishing a flexible spacecraft dynamics system with flywheel friction disturbance; b. converting the flexible spacecraft dynamics system with flywheel friction disturbance into a state-space form; c. constructing a flywheel friction disturbance estimator; d. constructing a flexible appendage vibration disturbance observer; and e. combining the flywheel friction disturbance estimator in the step c and the flexible appendage vibration disturbance observer in the step d with a nominal controller to obtain a compound controller; the compound controller compensating for flywheel friction according to an estimated value of a flywheel friction moment; and the compound controller compensating for flexible appendage vibration disturbance according to an estimated value of flexible appendage vibration disturbance.

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.

An electric propulsion device for a satellite equipped with at least four active thrusters exerting a parallel thrust upon a transfer, the device comprises means for detecting a thruster failure and means for reorienting the thrusters, and comprises means for computing a reorientation angle of the thrusters remaining active upon a failure of a thruster, the value of the angle being computed to reorient at least two of the remaining thrusters in order to cancel the total torque about the center of mass of the satellite.

A new apparatus and method for determining trajectories for hypersonic glide vehicles significantly reduces integrated, or total, heat load, with little reduction in time to distance and maximum range. The new approach identifies a trajectory having large phugoid oscillations and plotting a glide trajectory along the peaks of the phugoid oscillations. The glide trajectory is determined by calculating a first altitude that results in a maximum lift to drag ratio trajectory having damped or small phugoid oscillations, then calculating a different altitude that results in larger phugoid oscillations, and higher phugoid peaks, and finally plotting a trajectory from the first altitude that follows the peaks of the higher phugoid oscillation trajectory. The thus calculated trajectory can be input into a glide vehicle guidance system for controlling the trajectory of the glide vehicle from a point where it reaches the first altitude.

A space vehicle engine (10) comprising a chemical thruster having a nozzle (30) for ejecting combustion gas, together with a Hall effect thruster. The engine is arranged in such a manner that the nozzle serves as the ejection channel for particles ejected by the Hall effect thruster when it is in operation. The engine can deliver high thrust with low specific impulse or relatively low thrust with large specific impulse.