This answer mentions that Zvezda has S5.79 engines for reboosting the ISS. Wikipedia mentions that this engine has a burn time (ie. lifetime) of 2700 s. Dividing that lifetime by Zvezda's age (20 years) gives around 2 minutes of burn time per year. I think that station reboosts require longer burns, which would use up the engines faster.

Are the engines designed to be replaced in orbit? Have they ever been replaced?

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    $\begingroup$ The linked answer was incorrect in stating that "The Zvezda module's integrated thrusters are often used for reboost." $\endgroup$ Commented May 24, 2020 at 19:35

1 Answer 1


Zvezda's engines were used primarily in the very initial construction stages of the ISS. Most reboosts since 2001 have been performed by visiting vehicles such as Progress, Soyuz, and formerly, the Shuttle.


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