View source for Propellant production

[[File:Propellant production.png|thumb|600x600px]]
Propellant production for a Martian settlement will probably use water from the [[regolith]] and [[CO2]] from the atmosphere to produce [[Methane]] and [[oxygen]].

[[Electrolysis]] is used to produce hydrogen and oxygen.  The oxygen is stored for use as a propellant.  The hydrogen is combined with CO2 to produce methane and water using the [[Sabatier process|Sabatier]] process.  The water is stored for reuse, and the methane as the chemical fuel for the Methane-Oxygen (Methalox) propulsion system.

The image illustrates the process required to create the propellant for a large SpaceX Starship type vehicle over a period of two years ( an Earth Mars Synod).