Im not sure why Im answering your post

but you seem to think that a gyroscope will not change the momentum of a spacecraft.


if your spacecraft is spinning and then you stabilize the spacecraft by rotating the gyroscope and the spacecraft stops spinning then the gyroscope has changed the momentum of the spacecraft.

a student spinning by applying a force to a gyroscope

if the above student were inside a can in space he could use the gyroscope to manuver the can , much like space craft use them.

he applies a force to rotate the gyroscope then another to change the axis of he gyroscope in order to move himself and the gyroscope while standing on a swivel.

notice that no one pushes him and causes him to move by applying an external force on him or the swivel or the gyroscope , so if he were in a can in space this internal force he applies would rotate the can he is standing on.

just as newton describes it.
but not as imagegeek describes it.

3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.