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The ISS has spent two decades fighting drag caused by its large size and huge solar panels pushing through the tail-end of Earth's atmosphere only a few hundred kilometers above its surface.

Question: Is it possible to break down either the total delta-v or impulse delivered to the ISS over its lifetime by type of engine? If one specific individual engine unit stands out as deserving of special recognition, that would be interesting to know as well.

Presumably almost all delta-v or impulse has been imparted in orbit-raising, don't worry too much about separating any possible maneuvers of other types if they are included in the dataset and not easily separated. For that, I've just asked How often has the ISS's orbit been propulsive lowered intentionally?

note: I've used delta-v or impulse because as @Antzi points out the mass of the ISS has changed substantially over the decades and I want to avoid overly pre-constrain the answer such that an existing data base can not be used.

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    $\begingroup$ Worked the hardest in terms of delta/v delivered or newtons ? The ISS mass significantly increased over time. $\endgroup$ – Antzi Dec 27 '18 at 16:17
  • $\begingroup$ @Antzi that's an excellent point; I've made an edit. Thanks! $\endgroup$ – uhoh Dec 28 '18 at 0:12
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    $\begingroup$ I'm sure most delta v was made by Progress ships engines. But I have no data. $\endgroup$ – Heopps Nov 21 '19 at 8:37
  • $\begingroup$ @Heopps in that case, what engine would be the first runner-up? Maybe the difference is so large that not that much data is necessary. $\endgroup$ – uhoh Nov 22 '19 at 2:11
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Progress thrusters would be used the most as the vehicle eventually leaves ISS after few months. That being said, based on the location of thrusters, you can see that roll and pitch have a larger moment arm than roll thrusters. Therefore, roll thrusters work the hardest.

https://www.nasa.gov/pdf/167129main_Systems.pdf

To reference the comment by uhoh, there are different ways to boost the ISS:

  • Progress Aft of Service Module with DPO thrusters
  • Service Module Main Engine
  • Progress on DC Nadir with DPO thrusters
  • Cygnus
  • ATV (retired)
  • Space Shuttle (retired)

Two factors to consider when doing a reboost:

  1. You want to change the attitude of ISS as little as possible
  2. Use expendable thrusters when possible

Therefore, Progress SM Aft with DPO thrusters would be the desirable method, and it is the more common one. Is there is no Progress on SM Aft then the next choice would be SM main engine.

Progress DC Nadir can reboost but is is more complex because of a required attitude maneuver, and it is limited to no more than 0.7 m/s.

Cygnus did an experiment in 2018 to test reboost capability. It was successful, but it will be a long time before it can become a nominal operation.

ATV was also a preferred method, but it was complex because of the integration of the operation with MCC-Houston, MCC-Moscow and MCC-Tolouse.

Space Shuttle with RCS was also a preferred method when Shuttle was there, but sadly that operation will no longer be used.

In summary, Progress on SM Aft with DPO thrusters is the preferred method. The SM main engine option is only used if no Progress is attached on the aft port.

Progress DPO Thrusters

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  • $\begingroup$ Link goes to 404. Also does not answer the question Is it possible to break down either the total delta-v or impulse delivered to the ISS over its lifetime by type of engine? $\endgroup$ – Organic Marble Apr 23 at 19:18
  • $\begingroup$ The question also included if an engine unit particularly stands out. Hence my comment (and fixed the link) $\endgroup$ – fonsi Apr 23 at 19:22
  • $\begingroup$ Thank you for the thorough answer! So it seems that to "which type of engine" the answer is "Progress DPO thrusters" and together those did much more work than all Shuttle engines? $\endgroup$ – uhoh Apr 25 at 0:21
  • $\begingroup$ Yes, Progress DPO on SM Aft. Shuttle would only be there for 2 weeks max, and its propellant would also be needed for re-entry. Progress stays for ~6 months on ISS and is the preferred method since the capsule (and its thrusters) end up burned upon re-entry. $\endgroup$ – fonsi Apr 26 at 1:19

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