Sorry the title sucks. It's hard to be descriptive about this in a title. I did a cursory check of the other topics and I didn't see this and assumed I probably wouldn't. I get very most basic idea behind rockets, every action with an equal and opposite reaction and all that jazz. Something that I thought of today that kind of embarrasses me to not be able to figure out. If you had something that looked a bit like a satellite dish, but in place of the feed antenna there was a rocket motor with propellent exhaust facing into the dish. This entire setup is in the vacuum and weightlessness of space. Ignore energy lost to the exhaust heating up the dish, I'm just thinking about the motion and kinetic energy imparted. It would seem as though the initial acceleration of the thing would be in the direction that a rocket would normally go for a brief moment before the propellent then made contact with the dish. I guess, in a perfect transfer of energy, the thing would just sit there as the net momentum of these two reactions taking place cancels each other out. But something seems off about that, since the propellent is bounced from the dish out into space to not come back into contact with this machine again. It just seems odd that something would be sitting in space pushing matter away from it and itself not accelerating. I'm certain that I've made some error in my thinking one way or the other. Can someone please show me the light?