I'll be honest, Markjo, Tumeni - I've considered your arguments and read your literature...
Nobody, and I mean nobody, really goes into detail about how rockets behave in a vacuum. They try, but nobody, not even the rocket builders go into detail about how "newton's" law of momentum explains everything... It stills leaves a big question mark about the simple question of - how do you push against nothing? A gun explodes against a bullet. A rocket explodes against nothing.. A vacuum, which by definition pulls things away from an object; not remain stationary to cause an opposite reaction which is needed to propel another object the opposite way (like Newton said).
That being said, I don't discredit the argument that rockets push off their own fumes. It seems silly, but I might be missing something here..
But here's the problem... I have two ideas for how Rockets work. The first is that Rockets do propel themselves. Rockets take off, enter earth's orbit - and if they don't stay there = they use rockets again to leave orbit and point themselves at another target like the moon or mars, etc...
Why do they shut off? Possible cost restraints but I find this hard to believe. The earth's gravity is what slows the Lunar spacecraft before approaching the moon (to about 2,500mph) before they use thrusters again..
So, it seems like most of their speed and braking power were gained by orbiting earth and later by possibly orbiting the moon or just using earth's gravity to gradually accelerate the spacecraft back to earth.
Now here's the second theory: What if the rockets performed well within earth's atmosphere, then entered earth orbit - which in my opinion is solar winds going around earth consisting of some matter - then rockets are used briefly to exit the solar winds, at which time the spacecraft has enough momentum in a "limited vacuum" to go to there destination with course corrections on the way.
What about rockets working better in a vacuum? Why? Because the gas can exit the "thrusters" at a higher speed.
Okay, but rarely mentioned is that rockets also are freer from gravity and atmospheric friction which allows it to travel faster....
But, more importantly, rockets will work just as well in a "semi-vacuum" using a little bit of matter to "push off of" as I'm suggesting...
I'm gonna be mad when the final answer to "do rockets work in a vacuum" is - well, it depends on what you mean by a vacuum... An absolute vacuum or a semi-vacuum?
Either way it's an impasse... NASA builds the rockets and they say they work in a vacuum... I believe it's probably a combination of both "gas pushing on gas" and "gas pushing on matter" like jets do.