The Boeing Company

Timothy S Lui

Kangsik Lee

Gary E Lemke

Glenn N Caplin

Qinghong W Wang

Troy Allen Fontana

Alexander Jacob Sobel

Cecilia G Cantu

Christopher James Wasson

John Preston Charles Mills

A control system for reducing disturbance torque of a spacecraft is disclosed. The spacecraft revolves around a celestial body surrounded by an atmosphere. The control system includes processors in electronic communication with one or more actuators and a memory. The memory stores data into a database and program code that, when executed by the one or more processors, causes the control system to instruct the spacecraft to enter a safing mode. In response to entering the safing mode, the control system instructs the one or more actuators to align a principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body. The control system also instructs the actuators to rotate the spacecraft about the principal axis, where a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis.

Spacecraft attitude control strategy for reducing disturbance torques

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.

Energy efficient satellite maneuvering

Methods, apparatus, and articles of manufacture to minimize command dynamics of a satellite are disclosed. An example apparatus includes a steering law module to calculate a first set of vectors to maneuver a space vehicle, and calculate a second set of vectors based on projecting the first set of vectors onto a fixed plane. The apparatus further includes an attitude controller to generate an attitude command based on the first and the second sets of vectors to prevent an unplanned rotation by the space vehicle.

Methods and apparatus to minimize command dynamics of a satellite

Apparatus and methods for controlling a spacecraft for a transfer orbit. The spacecraft includes a propulsion subsystem with electric thrusters that are installed with two-axis gimbal assemblies. The spacecraft also includes a controller that identifies a target spin axis for the spacecraft, determines an actual spin axis for the spacecraft during the transfer orbit, determines gimbal angles for the electric thruster(s) that adjust the actual spin axis toward the target spin axis, and initiates a burn of the electric thruster(s) at the gimbal angles.

Reorientation of a spinning spacecraft using gimbaled electric thrusters

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.

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San Pedro, CA, United States of America

Timothy S Lui