It is possible to supply spacecrafts in orbit in cis-Lunar space with oxygen from fuel production facilities on the Moon or on asteroids. What is the size of this potential in-space oxygen market today? I would like to see estimates of how many active satellites there are in orbit and how much oxygen fuel they together consume for station keeping and other maneuvers after orbital insertion. And how much is lost by leakage if that is a relevant quantity. Especially for geosynchronous orbit separately since it is relatively easy to reach several satellites in a single supply run there.

I suppose that the space station consumes a significant fraction of all fuel in space because of its great mass and the atmospheric drag. Water and breathing oxygen for the ISS crew would also be part of the market demand.

Since it is oxygen that would be supplied from in-space, I'd like to see estimates of how much oxygen is consumed in relation to other volatilities (such as hydrogen, kerosene, hypergolic fuels, solid fuels, cold CO2, xenon, helium, whathaveyou).

  • $\begingroup$ Refueling on-orbit has been discussed. A major technical challenge is that many contemporary satellites were never designed for such refueling. This means that most require bespoke engineering, and some are just too complicated to be worth it. $\endgroup$
    – Innovine
    Jan 12, 2017 at 15:50
  • $\begingroup$ Satellites in orbit don't use liquid hydrogen, kerosene and liquid oxygen, they use hypergolic fuel. Producing kerosene like rocket petrol on an asteroid would be difficult, hydrogen and carbon must be mined and the hydrocarbons of RP1 synthesized. They also don't use solid fuel for station keeping and maneuvering. Refueling solids in orbit would be very difficult. $\endgroup$
    – Uwe
    Jan 12, 2017 at 16:54

1 Answer 1


BOE: 1000 active satellites, launched with 3 tons of fuel+oxidizer each for an expected lifetime of 15 years is 3000/15=200 tons of fuel+oxidizer needed per year.
Note: 3 tons is too much, as many satellites will have a total mass that's less than that. I could be an order of magnitude off.

Most of these will be hypergolics so no oxygen, the remainder is electric propulsion so no oxygen either. Oxygen is avoided because it's difficult to store long-term due to boiloff. In the current market, basically only the ISS would benefit from on-orbit availability of oxygen.

  • $\begingroup$ Of course with availability of in-orbit oxygen, the market could change. Still, transport from the Moon would be a serious problem due to boil-off. Maybe once aerogel insulated tanks become a reality this could change, as boil-off would become non-issue. But currently that stuff is far too expensive to use in bulk like that. $\endgroup$
    – SF.
    Jan 12, 2017 at 12:57
  • $\begingroup$ @SF Given Hobbes estimate, and if the Falcon Heavy becomes real and launches 22 tons to GEO for 0.1 billion dollar, the ISRU fuel industry would be limited to 0.9 billion a year in gross revenues out of which to finance the initial investment besides the operations. That is, in 15 years from now if all new satellites were to use oxygen fuel and were designed to dock and refuel. Hundreds of satellites many of which are worth more than a billion each and have safer options for life extension than docking with an oxygen bomb from the Moon. Irreplenishable hydrogen boil-off is worse than oxygen's. $\endgroup$
    – LocalFluff
    Jan 12, 2017 at 13:33
  • $\begingroup$ @LocalFluff: Assuming current market, with current prices and current set of destinations and launch frequency. That all can change if price per ton to GEO drops - say, thanks to refueling in LEO. Of course we'd need some impulse to invest in infrastructure like that - and I can see only one possible: a Mars colony. $\endgroup$
    – SF.
    Jan 12, 2017 at 14:35
  • $\begingroup$ @SF But the point is that fuel from LEO onwards makes up only an insignificant fraction of the cost of spaceflight. Even for the ISS the cost of launching oxygen from Earth is not an important cost fraction. $\endgroup$
    – LocalFluff
    Jan 12, 2017 at 14:56
  • 2
    $\begingroup$ The question and the estimate are both baffling to me. Satellites don't use very much fuel at all for station-keeping; electric propulsion with xenon propellant is vastly more appropriate for station-keeping than anything with an O2 oxidizer; getting to them to replenish their supplies itself would take more fuel than would be delivered. $\endgroup$ Jan 12, 2017 at 15:07

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