UPDATE: See Space News' NASA tweaks call for lunar lander concepts which links to:

The question Has NASA “gone south”? Why are astronauts needed to explore the Moon's south pole? and its answers highlight the recent US executive branch's indeterminately-funded mandate.

As far as I understand, the gateway will be in the loop and a stop-over for the astronauts, and the reason I think so is that getting to the moon is the raison d'être for the gateway, so it would be awkward if it wasn't used. Or, to quote someone famous; "I don’t see any reason why it wouldn’t be (used)."

The exact propulsive scenario is still of course uncertain, especially the trip between the gateway and the Moon, but is it possible to estimate how many stages of propulsion the astronauts will experience on the round trip? How does the total number of propulsive stages compare to the Apollo missions?

In the Ars Technica's Here’s why NASA’s audacious return to the Moon just might work the subsection What hardware are they planning to use? outlines a notional scenario. This might possibly be useful as an example "notional" scenario from which to make an estimate.

Question: In total, roughly how many stages will likely be used to get NASA astronauts to the Moon's south pole and safely back to Earth?

One? Two? Four? Eight?

See Ars Technica's in-depth article How much will the Moon plan cost? We should know in two weeks

From NASASpaceflight.com's NASA Launch Services Program outlines the alternative launcher review for EM-1, click for larger size:

NASA Launch Services Program outlines the alternative launcher review for EM-1

  • $\begingroup$ What do you mean by stages? Stages of space craft or stages of travel? I initially thought the question was asking how may space craft stages would be required, then I thought maybe it's stages of travel, such as: (1) Launch, (2) Earth orbit, (3) Travel to the Lunar Gateway, (4) Gateway stay, (5) Lunar decent, (6) Lunar exploration, (7) Ascent to the Gateway, (8) Gateway stay, (9) Return to Earth orbit, (10) Descent to Earth. $\endgroup$
    – Fred
    Oct 23, 2021 at 15:49
  • $\begingroup$ @Fred I see what you mean, there can be some ambiguity here. I meant it like the parts of the rocket we call stages; 1st stage, 2nd stage, where "SECO" is the cut-off of the second stage's engine for example. The sentence "How does the total number of propulsive stages compare to the Apollo missions?" had meant to clarify that. I guess I would have used "phases of travel" for those things you've enumerated. $\endgroup$
    – uhoh
    Oct 23, 2021 at 21:51

1 Answer 1


Pending ongoing litigation; Starship-HLS is NASA's selected human Moon lander.

Saturn V had 3 stages; Apollo CSM was 1 stage and the Apollo Lunar Module was 2 stages. SLS launch is 3 stages (well...); Orion ESM is 1 stage and Starship is 32 stages*. Granted; the tankers/super heavy's used for refuelling will be reused; so its production wise a smaller amount. But from an architecture perspective, each launch is 2 stages. So 36 total for the current plan; 6 for Apollo.
*There is uncertainty in total number of refuelling launches.

Starship-HLS Bat Chart

Apollo Bat Chart

I've also created Bat charts for the other HLS proposals if you're curious. (it's 20 stages for Alpaca and 14 for ILV with uncertainty due to N. of stages of CLV)

  • $\begingroup$ Thank you for your informative answer and hard work! I'm slowly wrapping my head around the magnitude of the scenario, but I'm almost there. To double check, the number of major propulsive events or burns the astronauts experience is roughly 8? (SLS: 1st & 2nd, Orion: NRHO insertion, HLS: NRHO exit, surface landing, surface launch, NRHO insertion, Orion: NRHO exit/Earth return trajectory) not much more than Apollo, it's basically the extra uncrewed fuel transports that produce the "total stage number" disparity? $\endgroup$
    – uhoh
    Oct 23, 2021 at 21:43
  • 1
    $\begingroup$ @uhoh Yes. In fact; the stage number experienced directly by the Artemis astro's is less; because Starship is a single stage lander whereas Apollo had a 2 stage lander. $\endgroup$ Oct 24, 2021 at 0:37

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