Thanks. So let me outline a possible mission architecture to see if I understand what you are saying. For clarity I am going to use the non-official terms “Starship-L” (the vehicle that lands on the Moon and never returns to Earth) and “Starship-T” (the LEO refueling tanker vehicle). Starship-L launches with crew to LEO, SH booster returns to Earth. Starship-T launches, refuels Starship-L and then returns to Earth. Starship-L leaves Earth for the Moon, enters lunar orbit, then lands on the Moon. Starship-L launches from the Moon and returns to LEO. Starship-L crew transfers to a Crew Dragon for return to Earth. Perhaps the simplest approach would be if the Crew Dragon could dock directly with the Starship-L. The Crew Dragon would be launched unmanned to LEO and wait for the rendezvous. I don’t see the need to involve the ISS in a crew transfer operation. What is the benefit? You wrote “let Starships return uncrewed for validation”. I’m not sure what you mean. The Starship-L vehicle does not have the ability to re-enter Earth’s atmosphere, right? The mission architecture I outlined obviates the need for Orion, which means no staggeringly expensive SLS launches and overall a huge cost savings. All that is required is two Starships and an F9 with a Crew Dragon. And the Starship-L is left in LEO for the next Moon mission. I do see a challenge in re-provisioning that vehicle for the next mission, but it should be possible to refuel it.
Could Starship-T carry 4-6 astronauts? If yes, no need for an F9 Crew, but transfer of the crew seems tricky.
Interesting idea. If Starship-T also had a functioning crew compartment (I think normally it would not) and it would already have the ability to re-enter Earth atmosphere of course, then it could be used to return the Starship-L crew. As you note, crew transfer would be the challenge. An EVA transfer would not seem to be the best approach; everyone would need an EVA suit (Dave Bowman’s successful Pod-to-Discovery helmet-less transfer is not a good model!) with all the training and cost and added risk that involves. So the two Starships would have to be able to dock, crew compartment to crew compartment, meaning docking hatches would need to be present. They could be in the nose just like the Crew Dragon. But then the two vehicles would have to first dock nose-to-nose, transfer the crew, then separate and turn 180 degrees to dock tail-to-tail for the refueling operation. One issue that crew transfer approach would solve would be re-provisioning the Starship-L for its next trip to the Moon. The Starship-T could launch with all the provisions needed and then the returning crew could transfer them before they made the final leg of the trip back home. That would probably add at least a day to the overall mission. I’m liking this scenario. Someone tell me what issues I’m missing. I enjoy discussing this stuff with you all.
How about a crew and cargo pod in the nose of Starship-T, while -T is refueling -L, the pod is transferred from -T to -L and the returning crew from previous Moon mission does the reverse? After the pod docks into -L, the crew leaves the pod into -L cabin taking the cargo with them. The pod stays with -L and the cycle repeats. You could have 3-6 -L cycle and 1-2 -T servicing the round trips.
I doubt NASA would be enthusiastic for crew to be on Starship-L while it is being refueled. So why not: Starship-L to LEO Get refueled Astronauts on Falcon-9 with Crew Dragon rendezvous, then Starship-L goes to moon and back and then reconnects with Crew Dragon that's been orbiting for a splash down landing
I think that is complicating the basic Starship design unnecessarily. It sounds like you are suggesting that Starship be split into two sections. Essentially that turns the entire vehicle into 3 stages; FH booster, Starship stage with engines and fuel tanks, and a detachable crew/cargo section on top of that which would also have to have its own maneuvering engines. Good point, but as I understand it for the upcoming F9 DM-2 mission the astronauts will be onboard during fueling, correct?
Yeah, on the ground. Refueling in orbit might be a bridge too far. Orbital refueling has never been done
Yet. Emphasis on yet. Orbital refueling is a critical component to Starship doing more than just getting to orbit. I am certain the first few attempts will be done without any humans on board.
More than a few ... transferring cyro methane and oxygen ... before the sun comes up around the horizon in less than 45 minutes ... sounds tricky. I expect more than one kaboom while they learn.
Why the time limit? Sunlight won't insta heat the fuel. Starship is going to get the Mars with usable fuel. There was a Tweet on this I think, but can't find it. Feed pipe is in liquid section of tanker and light acceleration does the transfer, that's pretty simple. Also hard to kaboom outside the atmosphere.
Could SpaceX create a shuttle for crew and cargo that would fit as payload in a Starship? They might need more cargo to the Moon than could fit in Crew Dragon. A third Starship, Starship-S, could meet the returning Starship-L in LEO. As the shuttles change places from -S to -L with crew and cargo, -T refuels -L. But would crew feel safe as payload?
The problem is that NASA will not/cannot human-rate (is this a verb?) Starship+Super Heavy in time for the 2024 mission. Or care to even try. And SLS and Orion is pretty mandatory. Not flying the first humans to the moon on that stack would take some major spin on the parts of politicians. “Who needs SLS if not for humans to the moon?” No tax-payer/politicians really cares about what cargo, satellites, landing systems or gateway pieces fly on, as long as the rocket they pay for is the one launching the humans with the flags and the photo ops.
This reminds me of the frankly ludicrous, we-have-one-shot-at-this 180 degrees maneuver of the Apollo stack while in translunar orbit. But hey it worked then, so why not now!
I know you are not defending SLS, but obviously it is the height of hypocrisy if SLS can be human-rated with just a few missions (maybe two?) while Starship could not be human-rated with many more missions since it will be able to be reused multiple times a year at least. I do think NASA could human-rate Starship in time for a 2024 lunar mission if it wanted to.* *Obviously SpaceX needs to accomplish a lot in the next two years to make that possible, but I would not bet against them.
Why would SpaceX need to human rate Starship for the moon mission when they have a perfectly fine human rated Falcon 9+Dragon 2?
I am talking about Dragon 2 staying in LEO and acting as the transfer ship to/from Starship going to the moon but as I am typing this I just realized that Starship isn’t human rated, that’s the whole point of this sub thread, and I need more coffee.