Chris Hadfield: We're onboard a spaceship. Which way are we pointing? We have to control which way we're pointing, because we're solar powered. We have to point our solar arrays at the Sun. We have to control which way we're pointing 'cause we want to be able to communicate with the Earth. So our antennas need to point in the right way for communication with satellites.
We have to control which way the Space Station is pointing even while we are at sleep. So we have sort of like an auto-pilot that whatever we've set it in it will keep that attitude going, just like an airliner. And we can control it as the crew are all awake using this display right here. It could also be controlled by the folks in Mission Control on the ground, either from Moscow or from Houston. But how do you actually turn the Space Station?
We have these huge spinning wheels, we call them "Control Moment Gyros" or "Gyrodynes" and with a little bit of torque on them, and instead of them turning, the whole space station turns. So we can steer our space station using spinning wheels and solar power. Nice efficient way to steer a spaceship.