This might have been answered before but it's something that has been bothering me. A rocket in space will move in a straight line. If I apply thrust, it still moves in a straight line unless I apply the thrust in a different direction. So unless I have rocket nozzles attached to the side, applying a thrust vector in some other direction, my rocket will go in a straight line -- well and good. Now, here's what I wasn't sure about. If said rocket is moving ballistically -- just tooling along in a straight line after I apply some thrust (say I do a burn for 1 second). Now I have a nozzle at the end of the rocket, towards the back, facing 90 degrees away from my main engine. What happens when I fire the small engine near the end, for just a second or two? Would the rocket start rotating and continue on it's original vector? So it continues n the path it had before, but in a little while it will be facing backward? Would the rocket start moving along another vector at right angles to my original, ballistic path, so that we're still moving in a straight line, but now instead of straight along my original path it's a straight line vector that's the sum of the small, right-angle engine's nudge and the original ballistic trajectory? (I know, both trajectories are ballistic strictly speaking, as they aren't under continuous thrust). Does the answer depend on how far off center my 90-degree-directional nozzle is? My intuition says yes, that if it's off-center the rocket will start rotating because whatever the rocket is doing (as long as it's not accelerating) the small thruster is moving one end of my rocket, but since the end is attached to the center of mass and there's no reason for that to move -- it will stay where it is "stationary" relative to the end of the rocket. But anyway, I was curious, because I was thinking about how to make a rocket take a curved path absent a local gravity field -- imagine being in deep space somewhere and you want to travel in a curved path. (Maybe you want to turn around because you forgot your keys or something and need to pick up a quart of milk at space A&P on the way home :-) ) Thanks in advance!