This topic has nothing to do with Q drops. Read up on astrophysics and you will learn that space is not a vaccum, but very sparse atomic matter.
Unlike jet propulsion, rocket engines carry both fuel and oxygen so they do not need air for combustion. The expansion of heated gas within the nozzle pushes matter (the rocket in front of the nozzle) forward. The nozzle is the area that allows thrust, not the ambient space around it.
Not an engineer, but worked for rocket engine company many yrs. Please take this discussion elsewhere.