I guess that once Starship prototypes are complete they should be pretty weather- and dirt-proof. They should be perfectly sealed and stainless steel is well-suited to life outside (though sometimes I wonder about the tough conditions by the sea in Boca Chica - there must be parts or equipment that rust and get full of wind-blown grit ... anyway ...)

But the parts are stored outside, final joins take place in buildings without doors and those workers climbing in and out of the hatches don't look particularly clean.

How does SpaceX avoid problems with dirt, grit and sea salt getting drawn into valves and engines?

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    $\begingroup$ My guess is the Soviet approach. Looser tolerances, more surplus force, tougher, thicker parts. If it can't withstand open hangar in Boca Chica, it won't withstand field servicing on Mars. $\endgroup$
    – SF.
    Mar 29, 2021 at 12:22
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    $\begingroup$ Carl, I'm sure that engines, valves and other critical parts are sealed until integration. But the tanks spend a lot of time outdoors and are completed in open buildings. Particles in the tanks must surely end up in the engines. If that's the case it's impressive that Starship can deal with this. I'm curious how SpaceX manages it. $\endgroup$ Mar 29, 2021 at 18:13
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    $\begingroup$ @CharlieEvans They'd absolutely have to clean out/purge the tanks after final assembly. Many rocket engines have been destroyed by things like a single loose metal washer left in a propellant tank. $\endgroup$ Mar 29, 2021 at 20:09
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    $\begingroup$ Propellant lines can have screens/filters in them. Sat through many meeting about whether it was worth going after a fleck of something on the screens. $\endgroup$ Mar 29, 2021 at 20:57
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    $\begingroup$ They were 1000 micron screens on the shuttle ntrs.nasa.gov/api/citations/20080031529/downloads/… $\endgroup$ Mar 30, 2021 at 11:42

1 Answer 1


The short answer is that nobody outside of SpaceX knows. However I imagine that those parts which need to be kept really clean (like the Raptors) are built inside in clean conditions.

They may wash the tanks out with liquid nitrogen before connecting Raptors, they might use security filters on the tank outlets and equipment might be designed to be rugged enough to cope with small quantities of impurities.

Or it might be a source of some of their engine issues (although I doubt that very much).

  • $\begingroup$ This is a guess, not an answer. $\endgroup$ Mar 30, 2021 at 10:59
  • $\begingroup$ Nobody outside of SpaceX knows. That is the truth of the matter as I said so all answers are going to be guesses unless Elon Musk turns up here and gives us chapter and verse on how they do it. $\endgroup$
    – Slarty
    Mar 30, 2021 at 13:31
  • $\begingroup$ Protip: If you do not know the answer, do not write an answer. $\endgroup$ Mar 30, 2021 at 13:44

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