currently, this recipe can only be crafted in standard assemblers. It is the only rocket component that cannot be produced in a steam-powered assembler. Logic suggests this might be an oversight. If so, adding the "crafting-with-steam" category to the recipe (at line 203 in prototypes/content/mid-game-recipies.lua) would allow it to be crafted in a steam-powered assembler, making rocket production on Lignumis entirely self-sufficient. This seems logical to me - is this what the author intended? If not, please let me know, and apologies for taking up your time! =)

I also thought about this:
Given that plastic is required for both processing units and LDS - and can only be obtained via chemical plants (which must be imported to the planet, just like generators) - the steam-powered assembler might not be all that critical. However, it would be a good idea to add the "crafting" property to the fuel recipe; that would at least make it feasible to implement. As it stands, you end up with a softlock (unless you haul fuel all the way from Nauvis), because progression requires steam-based research, which in turn demands gold from Lignumis.

Done