As it turned out, it can be used to easily obtain fuel and oxidizer from the atmosphere of the Red Planet.
Scientists from Portugal and France have studied the efficiency of the decomposition of carbon dioxide into carbon monoxide and oxygen in Martian conditions, and found that it will be significantly higher than on Earth. Even a fairly low-power device using cold plasma (about room temperature) can get large amounts of oxygen directly from the atmosphere of the fourth planet. The corresponding article was published in Plasma Sources Science and Technology.
Cold plasma, like ordinary plasma, is an ionized gas saturated with ions and electrons. The temperature of electrons in "cold" plasma is much higher than the temperature of ions, since the exchange of energy between these two types of particles is often difficult. In this case, cold plasma means a partially ionized gas with a fraction of charged particles of about a percent of their total number. The temperature of such a plasma, as a rule, is close to room temperature, which makes it safe to handle, and its creation requires only a small amount of energy.
The authors of the new work note that they have already tried to use cold plasma to accelerate chemical reactions in terrestrial conditions. Among other things, it was used to decompose carbon dioxide into carbon monoxide and oxygen. However, it is not very effective on Earth. The carbon monoxide produced by this method of decomposition of CO2, due to the relatively high temperature of terrestrial laboratories, was immediately oxidized again to carbon dioxide, which made the approach impractical. However, the researchers performed calculations showing that at a much lower Martian temperature and pressure, this factor will be negligible.
The pressure of the atmosphere on Mars is 160 times less than that of the Earth, and the average temperature is below -50 Celsius. This means that the re-oxidation of the produced carbon monoxide with the released free oxygen will take a long time under such conditions. This will enable the two gases to be separated and pumped into separate storage tanks.
The authors emphasize that their method is much more economical than the one proposed earlier, in which machines on Mars were supposed to receive carbon monoxide and oxygen from carbon dioxide by heating above a thousand degrees. Heating on a cold planet will inevitably be energy-intensive, in contrast to cold plasma.
Researchers propose using the breakdown of CO2 to produce rocket fuel from a mixture of carbon monoxide and oxygen. With its help, the specific impulse of the jet engine will be approximately 270 seconds. Although this is not much, it will not require the delivery of rocket fuel and oxidizer to Mars for the return flight. For the new method to work in the conditions of the Red Planet, a compact power plant with a capacity of 100 watts and above is sufficient. This means that even a small apparatus of the Curiosity type can produce quite a lot of oxygen there.
An alternative method for producing oxygen and rocket fuel on the Red Planet can be water electrolysis. However, for this it is required to find - the water there (in the form of ice) is concentrated only in the polar caps and frozen water bodies, sprinkled with meters of Martian regolith. Therefore, the new plasma method for producing oxygen is interesting at least as a safety net or for work in regions of the planet far from water ice.
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