Assume you have a thing: rocket, satellite, probe, etc, and you’re pushing it to mars or whatever, and you have an engine that, based on the comment states in consumer noble gasses as fuel, one would assume you have to provide the noble gas, correct?

So after you falcon9 the thing into orbit, and push it along, and it then uses this engine to go the distance, will it constantly increase or hit a max terminal velocity. In either case, would that not tell you how much fuel to give it; which comes down to “if it is powered by helium and we are supposedly running out of helium, how much helium would it use vs how much helium is available?”

Is that not a sound question?

The second part of the question is “if we give it one ton of fuel, how far can it get?”

Pretty simple MPG question in my mind...