Importance

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Abstract

A spacecraft attitude controller balances external torques, including those resulting from gravity gradient and those resulting from other orbital disturbances, to achieve a comparatively stable, neutral attitude or orientation. Torque is balanced by selecting spacecraft attitude Euler angles and angular rates such that orbital disturbances and cross-coupling inertial effects are cancelled by the external forces, based on Euler's equation. A spacecraft attitude torque-balancing controller and related method compares spacecraft attitude angles and angular rates with an orbit reference frame, and provides instructions to conventional momentum management and propulsion controls to responsively adjust the spacecraft attitude and angular rates. This feedback loop drives to zero (or an acceptably small quantity) the rate of change of the difference between spacecraft and reference attitude and angular rates, thus minimizing the net accelerations on the vehicle. A further method is provided to determine a desired physical structure and mass distribution of the spacecraft, needed to achieve torque balancing in a spacecraft attitude such that appliances, such as antennas, solar panels, and instruments, will have the required orientation once in their final on-orbit deployed position.

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First Claim