WASHINGTON — NASA has laid out the most detailed picture yet of how SpaceX's Starship will be fuelled in orbit for Artemis IV, the mission set to become the first crewed landing on the Moon in more than half a century, and the plan is far more complex than a single launch — involving a depot spacecraft, multiple tanker flights and two separate refuelling stops before astronauts ever head for the lunar surface.
The sequence was presented during an agency briefing in late October 2026 and reported on November 3, 2026, as debate continues over exactly how many launches the refuelling campaign will require. Estimates cited by NASA's safety advisers run as high as 22 launches, while SpaceX chief executive Elon Musk has said the true number will be closer to six or eight — a gap that reflects different assumptions about how much propellant each tanker can deliver, how much boils off while waiting in orbit, and how efficiently cryogenic fuel can be transferred between spacecraft.
What is not in dispute is the shape of the plan itself. Before any astronaut boards a rocket for the Moon, Starship must first prove it can be gassed up in space — a capability no spacecraft has ever demonstrated at this scale. Artemis IV will be the first mission to depend on it.
Illustration: A SpaceX Starship lunar lander docked to an orbital propellant depot above Earth, with tanker spacecraft nearby transferring fuel. (AI illustration)
What Happened
NASA's updated flight sequence, outlined in a concept graphic presented in late October 2026, describes a multi-phase choreography in Earth orbit. First, a dedicated propellant depot is launched into low Earth orbit. Then a series of Starship tanker flights lift off from Earth, each delivering liquid methane and liquid oxygen to fill the depot's tanks.
Once the depot is full, the uncrewed Starship Human Landing System — the tall, silver upper stage adapted for lunar landings — launches, docks with the depot and receives its propellant load. According to reporting of the plan, the lander then climbs to a higher "final tanking orbit," where it is topped up a second time from a resupplied depot, before departing for the Moon.
Only after those orbital refuelling steps are complete does the crewed part of the mission begin. NASA's Space Launch System rocket launches the Orion capsule carrying the Artemis IV crew, and Orion meets Starship in high Earth orbit. Two astronauts transfer to Starship and descend to the lunar surface, while two remain aboard Orion — a division of labour that echoes the Apollo missions, in which two astronauts landed while one stayed in orbit.
NASA says the staggered approach is designed to give schedulers more flexibility in timing the SLS launch and to reduce the total propellant Starship needs, partly because the plan takes Orion directly into low lunar orbit rather than the higher orbit used in earlier mission concepts.
The plan remains provisional. NASA has left open the possibility of turning to Blue Origin's Blue Moon lander instead if SpaceX cannot validate its orbital refuelling approach or complete an uncrewed lunar landing test by the end of next year, pending Blue Origin's own readiness — a fallback that underlines how much of Artemis IV now rests on a single unproven technique.
Illustration: NASA's Orion capsule meeting a Starship lunar lander in high Earth orbit, with astronauts preparing to transfer between spacecraft. (AI illustration)
Background
Artemis IV's place in NASA's lunar programme has shifted repeatedly. Under the restructured plan, Artemis III — once envisaged as the first crewed landing — became a low Earth orbit docking and systems test flight, in which the crew will test both lunar landers in Earth orbit rather than landing on the Moon. Artemis IV is therefore now the programme's first planned landing of astronauts at the lunar south pole, a region prized because its permanently shadowed craters are thought to hold water ice that could one day be turned into drinking water, oxygen and even rocket fuel.
Starship is central to that ambition because of its size. It is the largest and most powerful launch vehicle ever developed, designed to be fully reusable and to carry far more cargo and propellant than any previous spacecraft. But that size is also the problem: a Starship leaving Earth cannot carry enough propellant to reach the Moon, land and return on a single tank. It must be refilled in orbit, like a long-haul aircraft stopping to refuel mid-journey — except that no one has ever refuelled a vehicle of this size in space, and the fuel involved is cryogenic, stored at temperatures so low that it constantly boils off and must be carefully managed.
That is why the launch-count debate matters. A 2021 audit by the US Government Accountability Office estimated the lunar architecture could require up to 16 launches. During an October 2026 public meeting, Charlie Precourt, a member of NASA's Aerospace Safety Advisory Panel, cautioned that fuelling the lander could require as many as 22 launches. Musk disputed that figure on X, saying the actual number of refuelling flights would be closer to six or eight. The disparity reflects different engineering assumptions: how much propellant each tanker can actually deliver, how quickly cryogenic propellant boils off during weeks of orbital loitering, and how efficiently fuel can be pumped between two spacecraft moving at orbital speed.
Validating orbital refuelling is therefore a critical technical milestone for the whole Artemis roadmap. NASA and SpaceX are scheduled to conduct an initial orbital cryogenic propellant transfer demonstration ahead of full uncrewed lunar test flights. Until that demonstration succeeds, every downstream date — the uncrewed landing test, the crewed landing itself — remains an estimate rather than a schedule.
Illustration: Two astronauts on the Moon's south pole surface near a landed Starship, with Earth in the black sky above. (AI illustration)
Why It Matters
The refuelling plan matters for three reasons. First, it determines whether the Artemis programme can land astronauts on the Moon at all in its current form. Without orbital refuelling, Starship cannot make the journey; there is no backup propellant architecture waiting in the wings, only the Blue Origin alternative lander, which would itself need to prove its own readiness.
Second, the launch count translates directly into cost, schedule risk and complexity. Every additional tanker flight is another launch that must succeed, another rendezvous and docking in orbit, and another opportunity for delay. A campaign requiring 22 launches is a fundamentally different undertaking from one requiring six or eight — more like a sustained orbital logistics operation than a single mission — and it leaves far less margin for weather, technical scrubs or hardware failures.
Third, the technique has consequences far beyond the Moon. If SpaceX can demonstrate large-scale cryogenic refuelling in orbit, it unlocks a new way of exploring deep space: spacecraft that leave Earth partially empty and fill up in orbit can travel much further, carry much more, and be reused in ways that single-launch architectures cannot match. Mars missions, in particular, depend on the same idea. Musk has said Starship could head to Mars at the end of 2026 carrying Tesla's Optimus humanoid robot, with crewed flights possibly following in 2029 or, more likely, 2031 — timelines that all assume orbital refuelling works.
Conversely, if refuelling proves harder than expected — if boil-off is worse, transfer slower, or docking more delicate — the entire Artemis timeline slips, and with it the political and financial case for the programme. The safety panel's warning is best read in that light: not as a prediction that 22 launches will be needed, but as a reminder that the current plan contains large uncertainties that have not yet been retired by flight experience.
What Happens Next
The next step is the orbital cryogenic propellant transfer demonstration, in which two Starships are expected to dock and move propellant between them in low Earth orbit. That test will give engineers their first real data on transfer rates, boil-off and the behaviour of super-cold fluids in weightlessness — the numbers that will settle the launch-count debate one way or the other.
After that come full uncrewed lunar test flights, in which a Starship lander must fly to the Moon, land and return without a crew aboard. NASA has indicated that if SpaceX cannot complete an uncrewed lunar landing test by the end of next year, the agency could pivot to Blue Origin's Blue Moon lander, pending its readiness — a deadline that puts the refuelling demonstration on the critical path for the whole programme.
Meanwhile, Artemis III's Earth-orbit test flight will put the crew vehicles and both lander designs through their paces closer to home, giving NASA a chance to retire risk before committing astronauts to a lunar landing. The results of that mission, and of the refuelling demonstration, will shape the final Artemis IV flight plan — including how many tankers launch, how long the depot loiters, and when, precisely, astronauts finally return to the lunar surface.
For now, the picture NASA has published is a plan, not a promise. It shows a route to the Moon that is elegant in concept and demanding in practice: a depot, a fleet of tankers, two refuelling stops, a rendezvous in high Earth orbit, and then — if every step works — two astronauts standing at the lunar south pole. The coming year will show whether the choreography holds.
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FAQ
What is Artemis IV?
Artemis IV is NASA's planned first crewed landing on the Moon under the restructured Artemis programme, targeting the lunar south pole. After Artemis III became an Earth-orbit test flight, Artemis IV took over as the first mission intended to put astronauts on the lunar surface.
Why does Starship need to be refuelled in orbit?
Starship cannot carry enough propellant in a single launch to reach the Moon, land and return. It must be filled up in Earth orbit by tanker spacecraft delivering liquid methane and liquid oxygen to an orbital depot before it departs for the Moon.
How many launches will the refuelling campaign require?
Estimates vary widely. A 2021 Government Accountability Office audit estimated up to 16 launches; NASA safety adviser Charlie Precourt cautioned in October 2026 that it could require as many as 22; SpaceX chief executive Elon Musk has said the figure will be closer to six or eight. The gap reflects different assumptions about tanker capacity, propellant boil-off and transfer efficiency.
What happens if SpaceX cannot prove orbital refuelling?
NASA has left open the possibility of turning to Blue Origin's Blue Moon lander instead, if SpaceX cannot validate orbital refuelling or complete an uncrewed lunar landing test by the end of next year, pending Blue Origin's readiness.
What is the next milestone for Artemis IV?
An initial orbital cryogenic propellant transfer demonstration, in which Starships dock and transfer super-cold propellant in low Earth orbit, ahead of full uncrewed lunar test flights.
Sources
SatNews, "NASA Graphic Outlines Artemis IV Starship Refueling Architecture as Launch Estimates Vary," November 3, 2026.
Space.com reporting on NASA's Artemis IV Starship refuelling plan, as summarised November 3, 2026.
Everything Space, "NASA details complex, uncertain Starship refueling plan for Artemis IV moon mission," November 3, 2026.
NASA Artemis programme briefings, late October 2026, as reported by SatNews and Space.com.
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