100kg flywheels help hold attitude. The Zvevzda module[1] has engines, used rarely. When Progress supply ships are docked, their engines are used for adjustmen

100kg flywheels help hold attitude. The Zvevzda module[1] has engines, used rarely. When Progress supply ships are docked, their engines are used for adjustment. [1] http://en.wikipedia.org/wiki/Zvezda_(ISS_module) http://en.wikipedia.org/wiki/Zvezda_(ISS_module)