[chimere]

This actually uses control moment gyroscopes [1] in a scissored-pair configuration, the subject of my undergrad thesis. These differ from standard gyroscopes in that they are gimballed to produce a reaction torque. They are actually most commonly used on large spacecraft for attitude control, so the comment about "technology from the ISS" is quite relevant.

However, the statement that there are "two for redundancy" is dubious. The torque from a control moment gyro is not produced in a constant vector - the torque vector rotates with the gyroscope as it is gimballed. Thus, if there was only one gyro, some component of its output torque would be aligned with the yaw axis, which would create some rather unpleasant and dangerous effects. The scissored-pair configuration is required to cancel out the yaw torque.

[1]: http://en.wikipedia.org/wiki/Control_moment_gyroscope