Nitrogen (chemical symbol: N7) is the most abundant atmospheric element in the Earth's atmosphere, making up 78% of the total atmospheric gas. Mars, however, has less nitrogen in it's atmosphere, only 3% of the total atmospheric gas. This relative scarcity of nitrogen will cause an expense for colonists on Mars. Distilling the atmosphere is a rather straight forward operation in which the cooling needed in liquefying the carbon dioxide is mainly provided by evaporating the liquid carbon dioxide after the nitrogen has been removed. Likewise the power for compressing the carbon dioxide is partially provided by expanding the output waste through a turbine with a common shaft with the compressor.
The "nitrogen cycle" is an essential terrestrial process that produces organic compounds intrinsic to life on Earth. "Fixing" by lightning strikes or bacterial processes combine atmospheric nitrogen with other elements (such as hydrogen, producing ammonia) producing organic compounds useful to plants (sustaining growth and used in photosynthesis), thereby supporting ecosystems. Nitrogen can be found in amino acids, proteins and DNA, making it an essential component of life as we know it.
To maintain Nitrogen in a manageable, and useful liquid phase will require additional energy. The boiling point of nitrogen is -195.79 °C, so a temperature below this must be maintained through refrigeration.
The surface temperature of Mars will aid this effort as the average global temperature is approximately -63°C, so storage location of liquid nitrogen would not be inside habitats (where the average temperature should be as close to 23 °C as possible), but outside, on the cooler surface. This section reflects the personal position of Ioneill
- May be used to prepare dead bodies prior to disposal. Freezing bodies with liquid nitrogen and then powdering the remains (through vibration) may be a viable means to reuse valuable biomass (in greenhouses etc.).