Atmospheric processing

Atmospheric processing is the process of extracting substances out of the Martian atmosphere and use them as raw material for further processing. Unlike surface and sub-surface mining, the atmospheric mining does not require the movement of large amounts of regolith or rock with heavy machinery, nor is expensive transport per rover or railroad necessary. The atmosphere can simply be sucked in through a pipe at every location, and the processing is done inside of buildings. Also, the maintenance of all the mining machinery is in-house, which is a major safety advantage.

Collection of atmosphere

A device similar to a vacuum pump collects Martian air. The gas is compressed to be able to liquefy carbon dioxide.

Distillation

The atmosphere is cooled to remove water vapor as a condensate. As the gas continues to cool most of the rest of the water vapor is removed as frost. The dry gas is cooled further to remove carbon dioxide condensate. There will be more carbon dioxide than is needed for industrial purposes so some of it will be expanded to help power the compressors and to cool the incoming gas. Then excess CO₂ will be discharged.

Buffer gas for breathing

The balance of the remaining gas contains mostly nitrogen and argon which can be used as mixed as a buffer for oxygen to produce a breathable atmosphere. Carbon monoxide can be catalytically removed.

Nitrogen and argon

Nitrogen can be separated out for use as ammonia and nitrates in fertilizer and as nitric acid in industry. Argon is useful for industrial processes that must be performed in an inert atmosphere.

Wanted Substances

Dust

The Martian atmosphere contains variable amounts of dust, which consists of similar minerals like regolith. Electro-static filters may be used to collect the dust.

Water

The 0.03 % water vapor (H2O) is equivalent to about 10 % air humidity after adiabatic compression and cooling to around 1°C. A device similar to an air dehumidifier can be used to extract this water.