when Hydrogen is burned in a rocket engine.

the combustion produces a thrust.

then the recombination produces water.

you could burn a Hydrogen rocket engine inside a pipe
and still have all the water you started with.

given you have a big enought pipe.

and a centrifuge to capture and hold the water.
the thrust can spin the centrifuge , and the centrifuge can
seperate the water into H2 and O using membrane technology.

you now have a propulsion system for space travel.

3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.