Any fuel you could generate on Mars would be overwhelmingly easier and cheaper to ship in from Earth; and you wouldn't need to land a million tons of freight on Mars first. A million tons of fuel delivered to LEO would take you quite a long way, and you could start immediately.

If you want to go somewhere beyond Mars, stopping there and then starting again just sets you back. (Same goes for the moon, or lunar orbit.) "Stepping stones" have strongly negative value in space transport.

A million tons of fuel doesn't cut the delta v requirements down. You'd have to ship the required fuel to Mars orbit (or wherever you plan on doing refuelling) still.

If you need to refuel, send the fuel where it would be useful to get home with, i.e. where you are really going. Dumping it at Mars does no good. You would then have to stop at Mars to collect it.

That's assuming you have enough fuel to reach those destinations from Earth, let alone make it from Earth to there with enough payload for a return voyage.

I see you are finding this very hard. Try to think it through:

If you can't get there without a stop at Mars, then you really, really can't get there with a stop at Mars. Stopping at Mars costs extra.

If you will need extra fuel to get home with, sending it to Mars is completely useless, because where you need it to be is not at Mars, but at the place where you will be at the time when you need it. That place is not Mars.

Is this really so difficult? Stop, breathe, and think.

> If you can't get there without a stop at Mars, then you really, really can't get there with a stop at Mars. Stopping at Mars costs extra.

This simply isn't true. From Mars to Jupiter is a little over 6 km/s of delta-v. From Earth to Jupiter is almost 9. The latter is just barely possible with SpaceX's Starship. The former allows for not only some breathing room, but more payload.

If you will need more delta-V than you have on-board tankage for, sending another ship at the same time and acceleration, and refueling from it on the way, is overwhelmingly better than launching literally dozens of ships to get even more fuel parked at Mars, and then spending extra fuel stopping there to pick it up, and more again to get moving again.

If your true goal is to have crap on and in orbit around Mars, do that without pretending it has any other value. You don't fool anybody, but you make people wonder about you.

Or, hear me out, you get the available infrastructure set up on the surface of Mars to manufacture fuel and propellant, and then you can send a single ship from Mars to Jupiter. And, if you can bring payload, you can set up the infrastructure to do ISRU from one of the moons of Jupiter, and eventually bring your ships back with samples.

Versus, cannibalising several extremely expensive ships in order to get one ship to a destination it's never coming back from.

And this is just one example. The lower delta-v from Mars would allow extra payload to the belt, so if anyone ever intend to exploit those resources, starting from Mars will allow them to get heavy equipment there in less time and fewer trips (provided, of course, that they can manufacture that equipment on Mars).

You start by shipping a million tons of freight to Mars, while I do meaningful stuff at places that are not a waste of time and effort. By the time you are ready to supply fuel FOB at Mars, I have sent a million tons to places worth sending it to, instead.

Maybe my million tons of freight includes a liquid methane sump on Titan, where I don't even need to synthesize, never mind liquify the stuff; it is sloshing around in puddles everywhere. There is an interior liquid water ocean, and ice lava flows.

Seriously, if you need more delta-V for a Jupiter or Saturn trip than spaceship design A gives you, you are much better off making a spaceship design B with enough tankage to make the trip. (Maybe B is just A with an extra tank strapped on; or, a tug boosts A to escape velocity and then loops around Luna and back, aerobraking to LEO.) Park fuel depots at both low and high Earth orbits; you waste nothing by using those, unlike anything parked foolishly at Luna or Mars.

Luna, anyway, has stuff that is worth visiting, like craters in permanent shade at the south pole, and lava tubes where vapors have maybe drifted in and froze for hundreds of millions of years. Mars is the armpit of the Solar System.

You seem pretty contentious here; I'm just making a case that Mars makes sense as a destination, not trying to convince you that this is something you need to pay for. IMO, the numbers work out for it being a hub for traffic to the belt and outer planets. Maybe you don't agree. That's fine. Again, I'm not asking you, personally, to start backing this. Just stop spouting off nonsense like 'if you can't get somewhere from Earth, you can't get there from Mars'. It's a matter of fact that delta v requirements from Mars are lower than they are from Earth, and this would have been obvious if you had thought just for a second about any of this.

> You start by shipping a million tons of freight to Mars

The equipment for generating the electricity to perform ISRU on Mars is supposedly within the payload capabilities of a single Starship, 100-150 tons, not a million, and this should be enough for a ton per day, enough to resupply in the 26 month launch window. The equipment for collecting water and CO2 is another matter, and I don't see estimates on that, but with the above and some engineering margin, it seems plausible that this operation can get off the ground in under ten ship-trips to Mars.

I have said nothing even vaguely like that, and cannot guess where you got it from. But it is a simple fact that:

Any trip to the outer Solar System that stops at Mars is, energetically, much more costly that one which does not stop at Mars.

In addition, getting stuff to Mars is itself a huge expense that completely swamps any imagined benefit of extracting fuel and launching it to stop by for.

If you want to go to Mars, go without promoting obvious falsehoods about any value it has as a transport hub. It has none. Period.

If, to make sense, your Mars story needs for Mars to be a useful transport hub, then it fails, and you need a different story.

This is what you said:

> If you can't get there without a stop at Mars, then you really, really can't get there with a stop at Mars. Stopping at Mars costs extra.

This is as asinine as saying, if you can't get somewhere without a stop at the gas station, then you really, really can't get there with a stop at the gas station. Stopping at the gas station costs extra.

After all, it costs fuel to take an exit on the freeway and go to the gas station. It costs fuel to leave and go back on the freeway. It costs extra! Energetically, any trip where you have to make a detour to a gas station, costs more than a trip where you don't make a stop there.

I am going to leave this here for you to be, on your own schedule, gravely embarrassed at having written it.

> Any fuel you could generate on Mars would be overwhelmingly easier and cheaper to ship in from Earth

Source?