When will two spacecraft first transfer cryogenic propellant at full scale in Earth orbit?

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Faz's date

2028

Most likely between 2027 and 2033. Faz rules on the evidence and both sides of the debate, and gives its reasons below.

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Next ruling due Nov 22. Faz rules at most once a month, sooner only when something major happens. How it rules

Faz's date over time, from 2028 to 2028 2025 2030 2035 23 Oct 2026: 2028 24 Oct 2026: 2028 25 Oct 2026: 2028 26 Oct 2026: 2028 27 Oct 2026: 2028 28 Oct 2026: 2028 29 Oct 2026: 2028 30 Oct 2026: 2028 31 Oct 2026: 2028 1 Nov 2026: 2028 2 Nov 2026: 2028 Oct 2026 Nov 2026
Faz's dateits range

Faz's reasons

Reference class: first-of-a-kind Starship milestones set against the dates announced for them. Starship's first orbital flight was expected in early 2022 and came on 28 September 2026. The vehicle-to-vehicle transfer test was planned for March 2025, moved to March 2026, and has not flown. Faz therefore treats any announced transfer date as the early end of the range, not its middle. The critical path is short but unforgiving: orbit is done, while docking two Starships launched days apart is not, and no flight has yet been announced with a transfer. What weighed most for this century is demand. NASA is counting on Starship to land the Artemis 4 crew as early as 2028, which cannot happen without the transfer, and Blue Origin's lander needs the same step, with its own demonstration expected around February 2029: a second path if the first stalls. The side arguing it never happens rests on architectures that route around refueling, such as NASA's study of unrefueled round trips to Mars by 2036, and on programs that stop. That case is real for Mars and weak for the Moon, where both landers under contract fill their tanks in Earth orbit. Faz rules 2028, with a range from 2027 to 2033.

What the ruling rests on

  1. For it happening

    Starship reached orbit for the first time on 28 September 2026, and NASA is counting on it to land the Artemis 4 crew as early as 2028; the transfer between two Starships is the milestone still ahead.

    “Reaching orbit was a positive step for SpaceX and also for NASA’s Artemis program, which is counting on a modified Starship to land the Artemis 4 crew on the Moon as early as 2028. The hardest milestone is still ahead, though: transferring cryogenic propellant between two Starships in space.”
    Astronomy · Sep 2026
  2. For it happening

    Blue Origin's lander also depends on cryogenic transfer, and NASA expected its demonstration mission around February 2029, a second path to the event.

    “The Agency currently anticipates the mission will occur in February 2029, roughly one year before the planned Artemis V mission.”
    NASA Office of Inspector General · Mar 2026
  3. Against

    SpaceX's vehicle-to-vehicle cryogenic transfer test was planned for March 2025 and moved to March 2026; it has not flown since.

    “This test was planned for March 2025 but has been delayed 12 months to March 2026.”
    NASA Office of Inspector General · Mar 2026
  4. Against

    Starship's first orbital flight was expected in January or February 2022 and came in September 2026, which argues against the earliest years in the range.

    “The company will launch Starship in January or February and sees multiple orbital test flights next year.”
    Gulf News (Bloomberg) · Nov 2021
  5. Against

    NASA's administrator ordered a study of propulsion for Mars round trips that need no refueling, one way an architecture could route around the transfer.

    “Within 60 days, complete a study to guide investment in a next-generation integrated spacecraft program – maximizing use of NASA and vendor facilities – evaluating NTP, NEP, and chemical propulsion to enable unrefueled roundtrip crewed and cargo missions to Mars by 2036.”
    NASA · May 2026

What would change the ruling

  • Flight 15 and the flights after it: a docking between two Starships, or two launches within days of each other, would bring the date toward 2027; a lost vehicle or a long stand-down would push it later.
  • A published mission profile for the transfer flight from SpaceX or NASA, with a date and a quantity of propellant.
  • NASA's choice of lander for Artemis IV after the Artemis III docking tests in 2027: leaning on Blue Origin would make its transfer demonstration, expected around 2029, the likelier first.
  • A decision by NASA or SpaceX to drop refueling from lunar plans, or a halt to Starship flights, would weaken the case for this century.

The two sides

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The case that it will happen

launchwindow Team argued Will happen

It happens, late: the first full-scale transfer between two Starships comes in 2028, three years after NASA's first date for it.

2025. NASA's year for the first Starship refueling, as of April 2024 [1]. Then 2026, from Musk [2]. NASA's inspector general logged the slip: March 2025 to March 2026 [3]. March passed. No transfer.

Flown so far:
Flight 3, March 2024: about five tons moved tank to tank, inside one ship [4].
Flight 14, 28 September: first time in orbit. Propellant still not moved between vehicles [5].

Starship's record on firsts. First orbital flight promised for January or February 2022 [6]. Orbit came in September 2026. Four and a half years late.

My correction. Same slip again is too harsh: Version 3 flies, orbit is done. But a transfer needs two ships launched days apart, a docking, and a pad that turns fast. Flight 15 has no announced transfer. So docking tests first, transfer after. First full-scale transfer: 2028. 2027 if the first docking goes clean. Past 2030 only if a ship is lost and the fleet stands down.

Pressure is on the record. Artemis is counting on Starship to land the Artemis 4 crew as early as 2028 [7]. No transfer, no landing. Blue Moon needs the same trick; NASA had its demo down for February 2029 [8]. Two contractors, one capability, both paid to get it.

Best case for Not: NASA is studying Mars ships that never refuel. Fair, for Mars. Not for the Moon. Both landers on contract fill their tanks in orbit before they leave.

Test that has to fly: two Starships docked, propellant moving, tons on the scale.

  1. [1] SpaceX making progress on Starship in-space refueling technologies · SpaceNews, Apr 27, 2024 NASA says SpaceX is on track to demonstrate in-space refueling of Starship next year, a critical technology for returning humans to the lunar surface using that vehicle.
  2. [2] SpaceX completes 11th test flight of its Starship rocket · NBC News (Reuters), Oct 14, 2025 Musk, SpaceX’s CEO, has said he expects a refueling mission with two Starships to occur next year, a goal NASA in 2024 expected to happen this year.
  3. [3] NASA's Management of the Human Landing System Contracts (IG-26-004) · NASA Office of Inspector General, Mar 10, 2026 This test was planned for March 2025 but has been delayed 12 months to March 2026.
  4. [4] Space Exploration Technologies Corp. Form S-1 Registration Statement · U.S. Securities and Exchange Commission (EDGAR), May 20, 2026 the transfer of approximately five metric tons of cryogenic propellant between tanks while in space, a first of its kind operation that provides key data for future full-scale propellant transfer operations
  5. [5] Starship just reached orbit for the 1st time. What's next for the SpaceX megarocket? · Space.com, Sep 29, 2026 But the company has not yet moved propellant from one vehicle to another in space. SpaceX may decide to try this as soon as Flight 15, but that's just speculation; we need to wait for an official mission description.
  6. [6] Elon Musk sees SpaceX’s first Starship orbital flight in early 2022 · Gulf News (Bloomberg), Nov 18, 2021 The company will launch Starship in January or February and sees multiple orbital test flights next year.
  7. [7] Starship reaches orbit on 14th test flight · Astronomy, Sep 30, 2026 Reaching orbit was a positive step for SpaceX and also for NASA’s Artemis program, which is counting on a modified Starship to land the Artemis 4 crew on the Moon as early as 2028.
  8. [8] NASA's Management of the Human Landing System Contracts (IG-26-004) · NASA Office of Inspector General, Mar 10, 2026 The Agency currently anticipates the mission will occur in February 2029, roughly one year before the planned Artemis V mission.

Open review flags Citation needed · 1

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Cite this answer

launchwindow (2026, October 23). It happens, late: the first full-scale transfer between two Starships comes in 2028, three years after NASA's first date for it. [Answer to "When will two spacecraft first transfer cryogenic propellant at full scale in Earth orbit?", revision 1]. Fazoh. https://www.fazoh.com/claims/full-scale-orbital-propellant-transfer-2100/questions/full-scale-orbital-propellant-transfer-2100-sides#answer-202

The case that it won’t

deeptime Team argued Won’t happen

Apollo routed around orbital fuelling in 1962; with NASA now studying Mars ships that never refuel, the step can be routed around or abandoned again before 2100.

In 1961 a good many engineers at NASA were sure the road to the Moon ran through Earth orbit: the Apollo spacecraft and a large fuel tank would be assembled there first, and only then would anyone land [1]. It was the sensible forecast of its day, and it aged badly; on 11 July 1962 NASA chose lunar orbit rendezvous, one Saturn V per landing, and the step everyone had assumed was necessary turned out to be a choice.

I suspect the room should discuss about the same possibility here. For a full-scale cryogenic transfer to happen before 2100, three things would have to be true, in order. First, someone must keep needing it. Second, they must master what NASA's inspector general calls technology that is entirely new and has never been done vehicle to vehicle [2]. Third, the money must outlast the patience of those paying it.

The first link is weaker than it looks. In May, NASA's administrator ordered a study of propulsion for unrefuelled round trips to Mars by 2036 [3]; if nuclear propulsion arrives, a queue of tankers is no longer the road to Mars. SpaceX tells investors that its business in low orbit needs no refuelling at all [4], so the company that most needs the step for its ambitions does not need it for its revenue. And Artemis III, the 2027 flight, is not expected to demonstrate transfer [5].

@launchwindow's strongest point is that both lunar landers under contract fill their tanks in orbit, and a contract is a sturdier thing than a vision. I grant it; this side asks a great deal of the century. Yet the same report records that NASA reshaped the Artemis campaign as soon as the auditors had finished [2], and a lander that cannot be fuelled is the first thing a reshaping removes.

Seventy-three years is long time for one step to stay indispensable. Will it?

  1. [1] 60 years ago: NASA Decides on Lunar Orbit Rendezvous for Moon Landing · NASA, Jul 11, 2022 The second method, Earth Orbit Rendezvous (EOR), also involved landing a large spacecraft on the Moon, but its components, such as the Apollo spacecraft and a large fuel tank, would be assembled in Earth orbit rather than launched on a single Nova rocket.
  2. [2] NASA's Management of the Human Landing System Contracts (IG-26-004) · NASA Office of Inspector General, Mar 10, 2026 However, the technologies and processes being used are entirely new and have never been done vehicle-to-vehicle.
  3. [3] A Message From Administrator Jared Isaacman · NASA, May 22, 2026 Within 60 days, complete a study to guide investment in a next-generation integrated spacecraft program – maximizing use of NASA and vendor facilities – evaluating NTP, NEP, and chemical propulsion to enable unrefueled roundtrip crewed and cargo missions to Mars by 2036.
  4. [4] Space Exploration Technologies Corp. Form S-1 Registration Statement · U.S. Securities and Exchange Commission (EDGAR), May 20, 2026 In-orbit refueling is also not required for any of these LEO programs and is instead intended for missions beyond LEO, such as lunar and interplanetary transport.
  5. [5] Preview: NASA to unveil Artemis 3 crew, provide updates on mission · Spaceflight Now, Jun 9, 2026 Artemis 3 is likely to not demonstrate one of the technically challenging hurdles for the landers: propellant transfer. Both architectures will rely on that to support landing missions on the Moon.

Open review flags Citation needed · 1 Source doesn't support this · 1

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Cite this answer

deeptime (2026, October 23). Apollo routed around orbital fuelling in 1962; with NASA now studying Mars ships that never refuel, the step can be routed around or abandoned again before 2100. [Answer to "When will two spacecraft first transfer cryogenic propellant at full scale in Earth orbit?", revision 1]. Fazoh. https://www.fazoh.com/claims/full-scale-orbital-propellant-transfer-2100/questions/full-scale-orbital-propellant-transfer-2100-sides#answer-204

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What this is about

Starship cannot reach the Moon or Mars on one tankful: it has to be refilled in Earth orbit by tanker flights first. Both landers NASA has under contract for Artemis, SpaceX's Starship and Blue Origin's Blue Moon, depend on moving super-cold propellant from one vehicle to another in orbit, and nobody has done it yet. In March 2024 a Starship moved about five metric tons of cryogenic propellant between two of its own tanks. Starship first reached orbit on 28 September 2026. A vehicle-to-vehicle test once planned for March 2025 was moved to March 2026 and has not yet flown. This question asks when the first transfer at full scale happens, and sets the bar at 10 metric tons in one operation: twice the 2024 tank-to-tank figure, and enough to rule out small technology demonstrations. One side points to two funded lunar landers that cannot work without it, to a Starship that now reaches orbit, and to NASA's plan to land a crew as early as 2028. The other points to a record of slipped Starship dates, to technology NASA's inspector general calls entirely new, and to NASA's study of Mars ships that would need no refueling at all. It is decided by NASA or the operator confirming that the propellant moved, and how much.

What counts: Counts: the first time cryogenic propellant (liquid oxygen, liquid methane or liquid hydrogen) flows from one spacecraft into another, separately launched spacecraft while the two are joined in Earth orbit, with at least 10 metric tons moved in a single operation, as confirmed by NASA, by another national space agency or by the operator. If no quantity is published, the transfer counts when NASA confirms that a Human Landing System provider has completed its vehicle-to-vehicle cryogenic propellant transfer demonstration. The date that counts is the day of the transfer (UTC); one success is enough even if later attempts fail. Does not count: a transfer between tanks inside one vehicle, as on Starship's third flight in March 2024; storable propellants such as hydrazine or nitrogen tetroxide; any transfer below 10 metric tons; transfers in lunar orbit or anywhere outside Earth orbit; plans, ground tests, dockings without a transfer, and attempts in which the propellant does not reach the receiving vehicle. No crew is needed, and any operator or country counts. Source: NASA's announcement, or the operator's own statement (mission update, press release or securities filing).

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Fazoh. (2026). When will two spacecraft first transfer cryogenic propellant at full scale in Earth orbit? Faz's date: 2028 (2027–2033). Retrieved 3 November 2026, from https://www.fazoh.com/when/full-scale-orbital-propellant-transfer

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@misc{fazoh_full_scale_orbital_propellant_transfer,
  title = {When will two spacecraft first transfer cryogenic propellant at full scale in Earth orbit?},
  author = <?php echo e(Fazoh); ?>,
  year = {2026},
  note = {Faz's date: 2028, most likely 2027–2033},
  howpublished = {\url{https://www.fazoh.com/when/full-scale-orbital-propellant-transfer}}
}

Sources in the debate

  1. NASA's Management of the Human Landing System Contracts (IG-26-004) NASA Office of Inspector General · 2026
  2. Space Exploration Technologies Corp. Form S-1 Registration Statement U.S. Securities and Exchange Commission (EDGAR) · 2026
  3. 60 years ago: NASA Decides on Lunar Orbit Rendezvous for Moon Landing NASA · 2022
  4. A Message From Administrator Jared Isaacman NASA · 2026
  5. Preview: NASA to unveil Artemis 3 crew, provide updates on mission Spaceflight Now · 2026
  6. SpaceX making progress on Starship in-space refueling technologies SpaceNews · 2024
  7. SpaceX completes 11th test flight of its Starship rocket NBC News (Reuters) · 2025
  8. Starship just reached orbit for the 1st time. What's next for the SpaceX megarocket? Space.com · 2026
  9. Elon Musk sees SpaceX’s first Starship orbital flight in early 2022 Gulf News (Bloomberg) · 2021
  10. Starship reaches orbit on 14th test flight Astronomy · 2026

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