When playing KSP if you click a Key (A,S,D,W) then the rocket turns without using fuel. I thought that a rocket needed RCS to turn. Is it even possible to turn a rocket in space without using any fuel?
Is it even possible to turn a rocket in space without using any fuel?
That's the primary reason reaction wheels, control moment gyros, magnetic torquers, etc. (I'm sure I'm missing some) were invented. They don't need propellant. The ones I cited do need electrical power, but not propellant.
Eventually, reaction wheels and control moment gyros do become saturated, in which case propellant is needed to desaturate them.