How do satellites accelerate in space with thrusters? In my space exploration topic we are learning about satellites.  We need to know a bit about thrusters and what they do.  However I don’t know how the thrusters accelerate the satellite in space.  It would relate to newtons 3rd law and the thrusters firing are the action force however what is the reaction force that causes the satellite to accelerate?
 A: The propellant and satellite both push against each other sending the propellant in one direction and the satellite in the other. Get on a cart or ice skates with a big huge rock and throw it off. Same thing.
The propellant is pressurized (either by heating, reaction, or some other means) and then allowed to escape and expand. To do so, it needs to move, and to move it needs to push against something. It pushes against adjacent expanding propellant in a chain until the force is transferred to the satellite's structure which accelerates the satellite. Simultaneously, the satellite also pushes back against the expanding propellant which accelerates the propellant.
In that sense, the satellite is using the exhaust gas as a propellant and the exhaust gas is using the satellite as the propellant. They are each other's propellant.
You could also just eject huge solid chunks of material out of the back of a ship using a catapult mounted to the ship's frame. Just not mass efficient. It's all the same thing.
A: While skating on a frozen pond, anytime we push something away from us, we will also get pushed back just by doing this. So, if we threw a big rock that we have been holding in our arms all this while, the rock will be flung forward, and we ourselves will be pushed back as a result.
In space it is the same principle, as long as the rocket can push something away from it (might be propellant fuel, gas or anything else really), the rocket will end up getting pushed in the opposite direction. This push is what gets defined as "acceleration" on the rocket!
Hope it helps.
A: Everyone has noticed that when we release an inflated balloon, we observe that it leaves in the opposite direction to the flow of air that goes out, it is the principle of action and reaction.
https://en.wikipedia.org/wiki/Reaction_(physics)
It is remarkably illustrated in this video: https://www.youtube.com/watch?v=ruBfXIVSYZ8
