People breath gaseous oxygen. It is one of the supplies necessary for the life support system of a manned expedition to Mars. Without it, the crew and most other living things (including plants) could die of hypoxia over the course of a few minutes (in the total absence of oxygen) to a few weeks (with a long term deficiency of oxygen). Living things can also die from hyperoxygenation if oxygen is supplied at too high a rate. A supply of oxygen with the proper range of partial pressure and in proper proportion to carbon dioxide and other soluble gases is necessary to manned exploration of Mars.
Oxygen is also a useful oxidizer. This makes it useful for manufacturing processes and as a propellant. It can be used as a gas or cryogenic liquid, depending on the intended function.
Small amounts of oxygen are readily stored and delivered as compressed gas. Larger amounts of oxygen are best stored as either cryogenic liquid or generated chemically from storable solids. Oxygen can also be generated steadily from water electrolysis, although additional scrubbers are necessary to remove the toxic oxygen allotrope ozone, and care must be taken in the selection of electrolytes in order to produce an uncontaminated product.
Compressed or liquified oxygen is more chemically reactive than gaseous oxygen at 1 ATM pressure, and care should be taken in how it is stored.
|Molecular Weight||32 g/mol|
|Boiling Point||-182.96 oC|
|Heat of Vaporization||212.9 J/g|
|Liquid Density||1410 g/L|
|Liquid-Gas Expansion Ratio||875 @ 20 oC, 1 ATM|
|Gas Density||1.3 g/L @ 20 oC, 1 ATM|
|4.3 g/L @ Boiling Point, 1 ATM|
Pure gaseous oxygen is odorless and colorless. Liquid oxygen is odorless and clear with a blue tint.