This is a reaction wheel[1]. 10 ten years ago during my studies I did a presentation of how they're used by spacecraft for attitude control[2]. Never thought I

This is a reaction wheel[1]. 10 ten years ago during my studies I did a presentation of how they're used by spacecraft for attitude control[2]. Never thought I could have one in my pocket someday! ^^ [1]: http://en.wikipedia.org/wiki/Reaction_wheel [2]: http://en.wikipedia.org/wiki/Attitude_control