- Oxygen must be added to the breathing air inside the habitat.
- CO2 must be removed.
- Food must be provided.
- The temperature inside the habitat must be comfortable.
The challenge is the day and night rhythm as well as the lasting dust storms. Oxygen can only produced with light, either sunlight or artificial light. During the night or during a dust storm there is not enough sunlight, neither for direct lighting for the plants nor for photovoltaic powered electric light. The Biosphere 2 experiment has shown significant deviations from good oxygen conditions due to the day and night rhythm.
The first Martian settlement will probably be much smaller than Biosphere 2, making it even harder to keep a constant oxygen level. This article discusses solutions to mitigate this issue.
Buffering the gases
Big tanks of water may be used to buffer some amount of oxygen as well as CO2, since those gases are soluble in water according to Henry's law. A good side effect is the heat capacity of the water, helping to keep a comfortable temperature in the settlement.
Constant artificial lighting
Parts of the oxygen producing greenhouses may be lit at night, which requires stored electrical energy. The stored energy must be large enough to cover a few months of dust storms, whereas wind turbines may help to produce part of the needed energy.
- What is necessary to build such a water buffer? How much water is needed? How can the active surface of the water be extended (rinsing over lava stone, spraying in the air, etc.) and what amount of energy is needed to keep this technology running?