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O 8

Abundance: 0.15% atmosphere 46,6% crust

Oxygen (periodic table symbol: O8) is a chemical element that can be found in the atmosphere and in most minerals on Mars. Almost half of the mass of the Martian crust is Oxygen, bound up in various minerals. Oxygen is created in stars from the fusion of Carbon and Helium. Oxygen has 8 protons and the most common isotope is oxygen 16. O17 and O18 exist and are stable. Oxygen needs two electrons to fill its outer electron shell, which makes it a powerful oxidizer. (Only Fluorine is a more powerful oxidizer, but Fluorine is a fairly rare element.)

Alga producing oxygen

Relevance for life

The metabolism of human beings, animals and various microbes depends on oxygen. The atmosphere of Mars contains only 0,15 % oxygen, which is not enough to support animal or human life. If Oxygen is common in Mars' atmosphere, an Ozone layer will build up which will protect the surface from Ultraviolet light.


Oxygen can be produced in situ:

  • in greenhouses by plants.
  • in photobioreactors by algae.
  • by reduction of carbon dioxide from the martian atmosphere, or carbonate minerals via either molten salt reduction[1] or via MOXIE style solid oxide electrolysis.
  • by reduction of oxide minerals, either at low temperature in aqueous solution[2] or at high temperature in molten salt[3]. This is required to free up metals from many ores.
  • by electrolysis of water
  • by the decomposition of perchlorates in the soil.
  • by thermal decomposition of water through the Sulfur/Iodine[4] or Zinc/Sulfur/Iodine[5] cycles.


  • Propellant. Oxygen is often chosen as an oxidizer for chemical propulsion.
  • Atmospheric component. The standard Earth atmosphere contains 21% Oxygen.
  • Chemical reagent as an oxidizer.

Related Articles

Oxygenlunarp on Lunarpedia.