The reason an arrow, airplane or a rocket in atmosphere stays in one orientation during flight is unequal drag. The feathers/fletching on an arrow produce mor

The reason an arrow, airplane or a rocket in atmosphere stays in one orientation during flight is unequal drag. The feathers/fletching on an arrow produce more drag and the the arrowhead is dense and moves the center of mass really far forward. As air passes over it the center of mass is pushed back least and the part with more drag are pulled back more. In space there is no air so rotating the ship is trivial. Consider comets or planets that are constantly revolving. Also, don't confuse turning with changing velocity and direction or travel. In my previous example the ship would stay in constant motion even though it is turning a 180 degrees. The actual turn could be done with rockets or reaction wheels and by spending very little force to do it.