Ammonia

A colorless and pungent gas. While often used as a food or fertilizer precursor, here it is used as a component necessary to make fission reactor fuel after being processed via Uranium Ammonolysis (which takes [UF4](Uranium Tetraflouride) and Ammonia and makes Uranium Nitride).

Resource Extraction

Ammonia can be collected either from Laythe's ocean or from Jool's atmosphere. The ISRU Refinery being used with the former, and the Atmospheric Scoop for the latter. There is currently no tool available (unlike radioactive resources) to determine concentrations at a ship's current location.