Space Systems/loral, LLC

Christopher D Rahn

Donald W Gamble

John A Lehner

A method for controlling reorientation of a spacecraft's spin from a minor axis spin bias to a desired major axis spin after spin transition. A control system monitors rotational rates about the principal axes to detect a separatrix crossing of a polhode path therein. Controlled thruster firings resulting from spin rate information successively decrease and increase a characteristic parameter and capture the spacecraft during a spin transition to a desired major bias orientation. It is possible to monitor only .omega..sub.1 and .omega..sub.3 in an alternate embodiment.

Spin reorientation maneuver for spinning spacecraft

A method for controlling reorientation of a spacecraft's spin from a minor axis spin bias to a desired major axis spin after spin transition. A control system monitors rotational rates about the principal axes to detect a separatrix crossing of a polhode path therein. Controlled thruster firings resulting from spin rate information successively decrease and increase a characteristic parameter and capture the spacecraft during a spin transition to a desired major axis bias orientation. It is possible to monitor only .omega..sub.1 and .omega..sub.3 in an alternate embodiment.

The present invention is a method and apparatus to control a pointing trajectory of an aim point with respect to one or more targets for a momentum bias spacecraft in an orbit inclined relative to an equatorial geosynchronous orbit wherein the spacecraft is provided with an onboard computer capable of using orbit information available to the spacecraft and spacecraft hardware to move the aim point according to a predetermined tracking model which may be either time-varying or invariant. The tracking model allows the controller to remove short-term nutational and long-term orbit rate dynamical disturbances, beyond simple-order sinusoidal functions having a single frequency.

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Pleasant Hill, CA, United States of America

Christopher D Rahn