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When SpaceX first announced their plans to develop a re-useable first stage, what was the envisioned life span of an individual booster in total launches before retirement (expected typical and maximum potential)?

Now that SpaceX has demonstrated successful reflight of a Falcon booster, what is the currently projected life span in number of launches before retirement (again, expected typical and maximum potential)? Has the flight experience accumulated so far affected the original projections for either better or worse?

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  • $\begingroup$ The number of possible launches might be lower for highly stressed parts like the turbine and turbo pumps and higher for parts like tanks and the electronics. $\endgroup$ – Uwe Apr 1 '17 at 18:48
  • $\begingroup$ So, does that mean it isn't about re-flying specific boosters, but stripping down each landed booster to build flight-worthy units from mixed and matched used/new components for each flight? $\endgroup$ – Anthony X Apr 1 '17 at 18:52
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    $\begingroup$ I don't know the maintenance philosophy of SpaceX. But the bearings of the turbine and turbo pumps running at a very high rotational speed might be replaced after a few flights. A failure of a single rocket engine during flight could be managed, but if several engines fail shortly after the lift-of, the stage and the payload might be lost. Therefore the probability of multiple engine failure must be kept very low. When the central Merlin engine is lost, a successful landing of the first stage might be impossible. $\endgroup$ – Uwe Apr 1 '17 at 19:20
  • $\begingroup$ @uwe I was under the impression that aside from pumping chemically active cryogenic liquid, rocket turbomachinery isn't much different or more demanding than that of jet aircraft. The pump portion could be dealing with a rather harsh/demanding environment (high pressure LOX or LH2), but the combustion side of a turbopump should have about the same life expectancy as the hot section of your average jet engine, no? $\endgroup$ – Anthony X Apr 1 '17 at 23:22
  • $\begingroup$ @AnthonyX: The goal is indeed rapid full re-usability: land, re-fuel, liftoff again. Musk has consistently said that he wants to get to the point where there's no difference to airliners. $\endgroup$ – Jörg W Mittag Apr 3 '17 at 0:08
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Musk was quoted recently that:

He expects to get to the point that each Falcon 9 booster could be reused 10 times with no refurbishment, or 100 times with moderate refurbishment.

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The expectations of SpaceX have varied greatly over time. Experience has taught them many lessons.

This initial reuse had many components replaced. The goal is to understand why those components needed to be replaced, build them more robustly so that they do not need replacement.

As Mark Adler's answer notes, the first reused booster will not be reflown a third time, but future Mod 5 boosters (the context of Mark's quotation) will be more resuable as that model is meant to be the culmination of the lessons learned from reflight testing.

In addition to simple resuse mission (SES-10), SpaceX has declared in the past that rapidity is also important. Thus things like how to reset the legs will need modifications. (This is one of the assumed modifications in Mod 5). If it takes 3 days to unload a stage, remove the legs, swing to horizontal, drive it back to the pad, you cannot relaunch in 24 hours as is the goal.

Musk suggested that the Mod 5 design will allow 10 reflights with minor touch work (refurb). Then with more major refurbishment should be good for 100 flights or more. The idea being, the core stage, and most of the major components should be good. Some parts are good for 10 flights and then need to be replaced. Each landing attempt gives them more data on how parts weather the reentry and allow them to test ideas in how to make the weakest link parts, last longer.

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