How Things Work: Space Station Steering
How do you maneuver a million-pound spacecraft?
- By Roger Mola and Tony Reichhardt
- Air & Space magazine, August 2012
The station's attitude is corrected continuously by four identical Control Moment Gyros mounted near the station's center of gravity, on the backbone-like truss. Each CMG has a four-foot-diameter stainless steel flywheel that spins at 6,600 revolutions per minute. Onboard software changes the spin axis of the wheels so that, moving in unison, their combined angular momentum cancels, or absorbs, the torque that gravity or other disturbances impart on the station. Each CMG produces up to 190 foot-pounds of torque.
Here, astronaut Dave Williams handles one of the CMGs during a 2007 spacewalk.