"Full" Space or "Empty" Space?

(meaning of "full"-space:  not "full of matter", obviously, but rather composed of  a fine and invisible continuum fluid substance, the uncompressible ponderal  fluid dynamic ether reformulated by Ing. Marco Todeschini)

This is the covert question, after the Ing. Todeschini

(on the scientific dogma of the interpretation of Michelson-Morley's experiment after "Decisive Experiments in Moderne Phisics" by Ing. Marco Todeschini)

We all have some experience of Newton's 3rd Law of Motion or

"PRINCIPLE OF ACTION AND REACTION".

From the original Latin of "Philosophiæ Naturalis Principia Mathematica" by Sir Isaac Newton:

"Lex III: Corpus omne perseverare in statu suo quiescendi vel  movendi  uniformiter in directum, nisi quatenus a viribus impressis cogitur  statum illum mutare."

"Law III: Every body persists in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed".

Applying now the Principle of action and reaction on Earth (sea surface) :

Then we apply it well also in the Sky  (Earth's atmosphere) :

... especially if it is "low-cost" ;)

Finally, we are happy after successes already achieved on the Earth and in the Sky, and we are going to apply even in the Space our universal Principle of Action and Reaction, without the consent of Isaac Asimov's extraterrestrials, who love the diaphanous Sociobiological Peace in the Galaxy  (their essential concept: "human go home!" :))).

We will use an ordinary rocket, called "Rocky", by recommending to Rocky of not creating too much trouble.  From bottom to top in the image below, we look at what happens in three steps: terrestrial, "celestial", spatial :

But our good Rocky has done the same trouble:  a sorcery !

Rocky moves as well in the deep space ... "empty" (or "almost empty"), despite of the third law of motion, ie in defiance of the Principle of Action and Reaction !

So one question: how does our Rocky, after the initial sprint, once stopped in the space, to move again?

During the expansion into the void, how does the propulsive jet to get a reaction from the vacuum (or from the almost-vacuum)?

If the action of propulsive jet (addressed by the conical nozzle in a specific  direction)  is made up of trillions and trillions of molecules and atoms, in osmotic expansion in a vacuum at high speed, while the reaction of the cosmic space is constituted by a few particles  (not linked to each other, and not bound to anything else; few particles which can move freely like billiard  balls), as does Rocky to move?

Where is the Rocky's reaction that needs to move in the space?

During the expansion into the void, how does the propulsive jet to get a reaction from the vacuum (or better from the almost-vacuum)?

... spell, sorcery, illusionism !

Another problem: here we do not believe in sorceries.