Carbon dioxide

Carbon dioxide (chemical formula: CO₂) is a chemical substance that occupies about 96 % of Mars's atmosphere.

Molar Mass of 12(C)+32(O₂)=44

Biological significance

The metabolism of human beings, animals and various microbes depends on the oxidation of carbohydrates, resulting in carbon dioxide and water exhalation. Plants use the carbon from carbon dioxide to produce carbohydrates and release the oxygen back to the atmosphere, completing the cycle.

The reaction is: CO₂(carbon dioxide) + 2H₂O (water) + photons (light energy) → C_(n)H₂O_(m) (carbohydrate) + O₂(oxygen)+ H₂O (water)

Uses

• Food Preservation

• Photosynthesis by plants in greenhouses to create carbohydrates for plant metabolism.
• Synthetic materials, hydrocarbons using the Fischer Tropsch reaction process.
• Propellant production. Methane (CH₄) and Oxygen (O₂), through ISRU using the Sabatier process. The hydrogen comes from Electrolysis of water or is brought from Earth.
• Carbon using the Bosch reaction process. The Bosch reaction consumes hydrogen to produce carbon and water. The hydrogen can come from electrolysis of water.

The Sabatier process can be used in place of photosynthesis to complete the atmospheric part of the carbon cycle. Synthesis of carbohydrates from methane would be required to complete the carbon metabolic cycle without the use of plants. Or food can be supplied from Earth or Mars for a partial cycle, where methane from the Sabatier process can be stored for use as a propellant.