Spacecraft attitude control strategy for reducing disturbance torques

A spacecraft, comprising:

• a main body defining a principal axis;
• one or more actuators;
• one or more processors in electronic communication with the one or more actuators;
• and
• a memory coupled to the one or more processors, the memory storing data into a database and program code that, when executed by the one or more processors, causes the spacecraft to:
• instruct the spacecraft to enter a safing mode, wherein the spacecraft revolves in an orbit around a celestial body having an atmosphere;
• in response to entering the safing mode, instruct the one or more actuators to substantially align the principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body;
• instruct the one or more actuators to rotate the spacecraft about the principal axis, wherein a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis each time the spacecraft completes the orbit around the celestial body;
• and
• instruct the one or more actuators to rotate the spacecraft a predetermined number of rotations about the principal axis at a constant rate as the spacecraft completes a single orbit around the celestial body, wherein the predetermined number of rotations per orbit is determined by:
• N+½
• wherein a value N represents a positive integer including zero.

A method for reducing disturbance torques experienced by a spacecraft, the method comprising:

• instructing the spacecraft to enter a safing mode by a computer, wherein the spacecraft revolves in an orbit around a celestial body surrounded by an atmosphere;
• in response to entering the safing mode, instructing, by the computer, one or more actuators of the spacecraft to substantially align a principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body;
• instructing the one or more actuators to rotate the spacecraft about the principal axis, wherein a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis each time the spacecraft completes the orbit around the celestial body;
• instructing the one or more actuators to rotate the spacecraft a predetermined number of rotations about the principal axis at a constant rate as the spacecraft completes a single orbit around the celestial body;
• and
• determining the predetermined number of rotations per orbit, wherein the predetermined number of rotations per orbit is determined by:
• N+½
• wherein a value N represents a positive integer including zero.