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The plan for the ISS upon decomissioning is to deorbit the structure and let it fall into the ocean.

I get that we do not want extra debris in orbit but I would think that leaving the structure in a stable orbit may provide an opportunity to recycle/reuse the infrastructure in future missions. It is expensive to get things of this size to orbit, but if it already exists then it makes more sense to me to leverage the existing assets where possible.

So what would it cost to keep the ISS in orbit? I am not looking for total operating costs, or what it would cost to keep it operational, just the amount that it costs to maintain orbit. What would it cost to put it into an orbit that would be highly unlikely to create a problem for 100+ years? Would that even be possible?

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  • $\begingroup$ nasa.gov/mission_pages/station/expeditions/expedition26/… $\endgroup$ – PearsonArtPhoto Oct 2 '13 at 14:42
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    $\begingroup$ It isn't in a stable orbit; it's present orbit decays as much as a kilometer every month. Besides it was constructed over the years module-by-module. There's a grand animation of it somewhere on the net ... let me see if I can get hold of it $\endgroup$ – Everyone Oct 2 '13 at 14:44
  • $\begingroup$ tietronix.com/creative-services/space-animation $\endgroup$ – Everyone Oct 2 '13 at 14:49
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    $\begingroup$ Sorry I removed the word stable... I just meant that it was in control. And I get that it was build over years... which is all the more reason not to just let it crash back to earth if we can reuse/recycle it sometime in the future in orbit. $\endgroup$ – Chad Oct 2 '13 at 14:57
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Yes, it is unfortunate that the space station is not quite fully in space. It is in Earth's upper atmosphere, which is why it requires such frequent reboosts.

From this Wikipedia entry:

The ISS requires an average 7,000 kg of propellant each year for altitude maintenance, debris avoidance and attitude control.

...

Multiple supply vehicles are required to satisfy the ISS's 7,000 kg annual average propellant need. The current plan for six Progress M1 spacecraft per year meets that need.

A good working number for a Progress launch is around \$50M. So about \$300M a year just for the propellant.

There would be additional costs to execute the maneuvers. Progress does the maneuver itself (you don't transfer propellant to the station for the reboost), but I don't know if the docking and reboost maneuver can be done without people on board ISS. If you need people, then that vastly increases the orbit maintenance cost, since you need to resupply people as well, and their life support resources, and operate the whole station.

Yes, it would likely be cheaper in the long run to send a whole bunch of Progress vehicles to boost the orbit, since the atmosphere decays exponentially. But only if your only objective is to keep ISS from augering in. You would then pay the penalty for less payload per launch to ISS at the higher altitude. There is a sweet spot where you minimize the total cost of propellant for reboost and up mass to the station. I suspect that that was a factor in determining the current ISS altitude.

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  • $\begingroup$ Thank you that is exactly what I was looking to understand. $\endgroup$ – Chad Oct 2 '13 at 17:26
  • $\begingroup$ I think you overstate expenses because not all of the Progress payload is propellant. One example I found (spaceflight101.com/progress-ms-04/cargo-manifest) shows propellant taking only 710 kg out of 2442 kg total, ie 29%. So if we send up nothing but propellant, 2 launches a year will be enough (instead of 6). Of course, this assumes Progress can be fitted with tanks large enough and that it will be able to stay up for half a year, neither of which a given. $\endgroup$ – Lesser Hedgehog Aug 3 '17 at 2:15
  • $\begingroup$ The maximum Progress M refueling module propellant is 850 kg. For Progress M1, it's 1700 kg. Not many M1's flew. It was mostly M's. $\endgroup$ – Mark Adler Aug 3 '17 at 3:53
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NASA's 2014 budget for the ISS is about $3B and this covers about half the cost with the other partner nations covering the rest of the costs.

The mission has been extended to 2020; it could be further extended to 2028 but the station isn't really designed to last beyond that. The rapid day-night cycle in low earth orbit causes metal fatigue and the solar panels have a limited lifespan as well.

The Russian segments might be removed from station to build a new Russian station but there is no plan to keep any of the US components. End of life for the station will free the budget to build better stations.

The Chinese will be flying their station by then. Hopefully there will be commercially operated stations as well. The lessons learned on ISS will be put to use.

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    $\begingroup$ Note that the question specifically asked for the cost to maintain orbit, not the total operational cost. $\endgroup$ – Mark Adler Oct 2 '13 at 16:12
  • $\begingroup$ @MarkAdler: (+: The question only mentioned cost in it's earlier avatar ; the entity making the answer will have to update the answer - if they so desire. $\endgroup$ – Everyone Oct 2 '13 at 16:21
  • $\begingroup$ Maybe I'm not looking at the edited versions right, but every version of the question asks the cost to keep ISS in orbit. $\endgroup$ – Mark Adler Oct 2 '13 at 16:36
  • $\begingroup$ Welcome to Space Exploration! As has @MarkAdler noted, the OP's question was regarding costs to keep the ISS in orbit, so that would of course be merely a fraction of total operational cost to run it occupied, with experiments in progress. Now, your answer is still a good overview of total cost to maintain the ISS operational (+1 BTW), so I suggest - and it's not unheard of, let alone unacceptable - to simply post a new question that would fit your answer and then self-answer it. Think of it as merely organizing things around, so they're posted where they belong, making them easier to find. Cheers! $\endgroup$ – TildalWave Oct 2 '13 at 18:51
  • $\begingroup$ @MarkAdler I think orbital maintenance would fall under "Spacecraft Operations" in the ISS budget. Spacecraft Operations was $812 M for FY 2005 budget. Unfortunately NASA's website is down right now but here's a chart you can view if you have a google account docs.google.com/spreadsheet/… There are plans to test a plasma drive prototype on ISS which could dramatically lower the cost of doing station keeping in the future: en.wikipedia.org/wiki/… Peter $\endgroup$ – peter Oct 3 '13 at 3:37

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