There are 3 basic strategies to get to the moon. Direct is the is the first, the ship/capsule takes off from Earth goes to the moon, lands and then some part of that capsule/ship takes off from the moon and returns to earth. Because you’re carrying LOTS of weight you don’t need at various points (e.g. the reentry shield on the capsule is dead weight as you land on the moon) the whole thing is VERY heavy. The rockets to do this are immense (e.g. the early NOVA concept https://en.wikipedia.org/wiki/Nova_(NASA_rocket) later repurposed but never used for mars exploration). The other two alternatives are Earth Orbit Rendezvous (EOR) or Lunar Orbit Rendezvous (LOR). In EOR, you go up to a waiting lunar specific lander board it and use it for the earth to moon trip land and return to your Earth/space vehicle. This is the Von Braun/2001 model. It’s one weakness is it usually requires in space refueling of your lunar transit/lander vehicle. This is kind of what I suspect the initial SpaceX model SEEMS to be headed for with a combination of Dragon Crew, Starship cargo/fuel ferry, and Lunar Starship for transit and landing. The Apollo (and current Artemis) use LOR, with Apollo sort of used a mixed model to keep the LEM as light as possible (for a great dramatiztion of this find episode 9 of From the Earth to the Moon, also good discussion of LOR vs EOR). I think SpaceX/Musk have realized lunar Starship is overkill for the task presented, thus making EOR more feasible. They also know Starship overall depends on refueling; if they can’t do that it is kind of game over for Starship for any purpose other than LEO delivery of cargo/ satellites.
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I suspect that any form of realistic near term space propulsion will wait for much higher energy densities than chemical propulsion. But not in the form of insane accelerations as much as low, fractional G accelerations for very long time frames with tiny amounts of reaction mass ejected at extraordinarily high velocities.
Unfortunately, this type of propulsion will work only once outside of a deep gravity well. You need 32/ft/sec just to hover in the earth’s g field.
I’m guessing the energy density we’d need would involve fission. Fusion just doesn’t seem like something we’ll figure out anytime soon. Maybe we can use Jupiter as a fuel depot. Isn’t it mostly hydrogen?
But hydrogen is of no help with a fission power source, except perhaps as a reaction mass. Water would be a better reaction mass, you could also use it as shielding, not to mention drink it.
I don’t know if there is elemental H in Jupiter’s atmosphere but there is damn sure abundant ammonia NH4 from you can get all the hydrogen you want plus some. I suspect they will really want tritium
I was thinking reaction mass. I haven’t kept up with the Jovian planetary composition info. In the old days they said it was probably hydrogen and helium in the atmosphere but maybe things have moved on. But whatever the gas giants are made of I wonder if they could be a reaction mass filling station for long voyages to the Kuiper Belt.