Mare regolith (high ilmenite, FeTiO₃, content) preferred; ~45% of all lunar regolith by mass is oxygen
By mass, ~45% of lunar regolith is oxygen, locked into oxides. Three production pathways: (1) hydrogen reduction of ilmenite (1-2% yield, simplest), (2) molten regolith electrolysis (Helios), (3) FFC-Cambridge molten-salt electrolysis (high yield, low efficiency). Oxygen is propellant (LOX) and life support. Israeli startup Helios + ICON + NASA Glenn all developing systems.
Note: MOXIE (oxygen demonstrator on Mars Perseverance) does NOT apply to the Moon — it splits CO₂ from Martian atmosphere. Lunar O₂ ISRU is harder: no atmosphere, energy-intensive solid-state chemistry, requires sustained power (which is itself a separate ISRU problem). No flight demonstration yet at lunar surface as of May 2026.