I wonder how satellites manage to always face earth with the same side. I know they have small rocket motors for station keeping, but in the absence of any athmosphere, they would have to perfectloy control thrust to keep the satellite from spinning every so slightly. Is there anything else aboard a satellite that can effectively zero out any torque, in any direction?

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    $\begingroup$ The first satellites did tumble. To avoid any unwanted rotation and keep the attitude of the satellite stable is difficult, but this problem is solved by very precise control of the thrusters. Another method is the use of rotating reaction wheels. $\endgroup$ – Uwe Feb 6 '18 at 10:18