In a discussion associated with this answer a comment includes the following:

The ISS is the only spacecraft in the world that has experience with regular on-orbit refueling.

What is the extent of on-orbit refueling experience at the ISS? Which fuels? which spacecraft?

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    $\begingroup$ Mir also did refueling via Progress I believe. $\endgroup$
    – geoffc
    Dec 14, 2020 at 0:56
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    $\begingroup$ @geoffc Salyut as well. en.wikipedia.org/wiki/Progress_1 $\endgroup$ Dec 14, 2020 at 16:10
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    $\begingroup$ @geoffc That doesn't make the statement above false. $\endgroup$ Dec 15, 2020 at 8:28
  • $\begingroup$ Does electricity count? Not that I'm aware of using ISS to 'recharge' a spacecraft. $\endgroup$ Dec 15, 2020 at 17:52

2 Answers 2


The propulsion system of the Service Module (public relations name: Zvezda), part of the Russian side of the ISS, is refueled by Russian Progress spacecraft, and formerly by European Automated/Ariane Transfer Vehicle (ATV) spacecraft.

Both Progress and ATV spacecraft deliver approximately 850 kg of propellant to the ISS.

The Service Module uses storable dinitrogen tetroxide and unsymmetrical dimethylhydrazine propellants.

The propellant is transferred through ports on the docking interface.

This schematic drawing shows the tankage in the midsection of the Progress.

enter image description here

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    $\begingroup$ @ikrase Russia owns their side of the ISS and the Progresses. It's up to them to manage it; it seems unlikely they would cripple themselves. $\endgroup$ Dec 14, 2020 at 5:04
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    $\begingroup$ It doesn't seem impossible that Russia might back out of the ISS someday before the USA and European-aligned parts. $\endgroup$
    – ikrase
    Dec 14, 2020 at 5:21
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    $\begingroup$ @OrganicMarble You mean, like the US did for almost a decade? $\endgroup$ Dec 14, 2020 at 12:26
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    $\begingroup$ @manassehkatz-Moving2Codidact Yeah, in "highly implausible intervention" I was imagining Elon ripping his shirt off to reveal the Superman logo and doing something like that. However, I would be surprised if that happened. $\endgroup$ Dec 14, 2020 at 15:55
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    $\begingroup$ @manassehkatz-Moving2Codidact: The MVAC, even at minimal thrust (and I don't even know off the top of my head whether it is throttlable at all), would rip the station apart. When the Shuttle reboosted the station, they didn't even use the OMS, they only used the RCS thrusters. For Cargo Dragon, they'd use the Dracos, I guess, even the SuperDracos would be too powerful. $\endgroup$ Dec 14, 2020 at 17:06

In addition to the standard operational refueling missions that are part of normal station-keeping operations, there have also been experiments performed that studied in-space refueling.

In particular, three phases of the NASA Robotic Refueling Mission have been completed, which simulated on-orbit refueling of a satellite not designed for refueling. A module was installed on the outside of the ISS that mimicked the fueling connections on a typical satellite. Note that "fueling connections on a typical satellite" here means the kinds of connections, valves, seals, etc. that you would find on a satellite not designed for refueling, to be only used once, on the ground, for initial fueling of the satellite.

Using these connections that were never intended to be re-used and never intended to be used in-flight, the RRM successfully demonstrated on-orbit refueling of hypergolics, oxidizer, and cryogenics.


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