This question already has an answer here:

Self explanatory:

In Dune, a central point is that the guild needs the spice melange for space travel.

So how did humans get to Arrakis/Dune in the first place then?

marked as duplicate by Valorum, Paulie_D, Politank-Z, Rebel-Scum, TheLethalCarrot Jul 28 '18 at 8:21

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