Lunar Settlement Artificial Atmosphere
The lunar colony will have a pressurized selection of acceptable gaseous environments. We have experimental knowledge with some artificial atmospheres,say, space stations like ISS or the MIR. Yet, we need to experiment more on the effects of long term exposure. On the Moon, the atmosphere will be made in accordance with the architecture followed. Some variables like the use of Air Locks, the thickness and materials of the walls may change the gas composition, pressure and other variables.
Gas Combination
See also: Atmosphere
Full oxygen Atmosphere or gas combination?. Pure Oxygen was used in the first Gemini Missions and it is a fact that oxygen will be a major by-product of the manufacturing activities on the Moon. It would be very easy to fill reasonable big spaces with Oxygen. However, in a long term exposure, pure oxygen becomes poisonous.[1] A combination of one or more inert gases with Oxygen would allow normal life and proper oxygenation. An example: a mix of 80% Helium and 20% oxygen. (a mix with about 60% oxygen would be ideal)
Nitrogen would be used on the moon as nitrates, part of the Plant Nutrients. The Moon does not have any trace of Nitrogen; therefore, this gas would be imported from Earth. It is very easy that nitrogen leaks from the solutions getting dissolved in the artificial atmosphere. An strict control has to be used to ensure the proper utilization of nitrogen. Other gas that will be present in the artificial atmosphere are CO2 and H2O.
Lower Pressure
Plants [2] and Humans can live in lower pressure atmospheres properly oxygenated. The limit is clear: when the vapor of a liquid inside equals the pressure outside, the liquid boils. Blood and other body fluids will boil if an abrupt drop of the pressure occurs.
We would need to lower the pressure inside the buildings to lower the force applied to the walls (somewhere around 40kPa would be ideal for many structures). Also, precise atmospheric pressure controls would be needed to prevent gas leaking.
