Am I misunderstanding the chain or is it impossible to make rocket fuel on Gleba without shipping in coal?
With the Simple Explosives, raw coal is a requirement for the production cycle to get offworld.
Rocket Fuel < Explosives < Basic Explosives < Coal
Coal can be produced on Gleba via synthesis, but is locked behind Rocket Batteries, a late stage AGRI science.
Without another recipe for Basic Explosives, the production chain is broken for a Gleba start, and requires Fuel or Coal to be shipped in for any other playthrough.
Suggestion: Alternate recipe for explosives: In Biochamber: Sulphuric Acid + Carbon + Bioflux = Explosives
Sulphuric Acid is obtainable on Gleba via vanilla processes, or a Natural Gas vent, and Bioflux the same way. This recipe would also continue the requirement of one liquid and two solid ingredients for explosives.