CO2 removal system for Manned Mission beyond LEO using deep space radiators and solar heaters
Jordi Paredes Garcia
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The current spacecraft technology to remove CO2 generated in manned missions uses mostly zeolite filters, which break down relatively easy; this has caused multiple problems over the last decades. The current solution has been to replace the defective components sending replacements form Earth, but this is only viable for missions close to Earth, e.g. ISS. Once humans require longer duration missions without Earth access, highly reliable CO2 capture needs to be implemented. There is no current technology that captures CO2 levels for long duration missions. Gaseous CO2 can be captured cryogenically, and the different solidification temperatures between water, carbon dioxide, nitrogen and oxygen become the key parameters of this system. It is important to note that human generated organic contaminants freeze at higher temperature than CO2. These contaminants will be captured prior to CO2 solidification. The medical community has determined that 5000 ppm in volume of CO2 is the maximum allowed concentration within an 8 hour working period for humans. Generally levels are required to be below 600 ppm. Every astronaut generates around 1Kg CO2 / day which needs to be removed from the cabin air continuously. This system consists of staged Two-Phase Heat Exchangers (NTR: 49561), to selectively solidify water, trace contaminants and carbon dioxide. Deep space radiators provide the required cooling power, and solar heaters deliver the necessary heat to evaporate all the solidified species, during the system cycles. This is why, for missions beyond LEO, that no power is required. The energy requirements are passively collected from space. (Only a small amount of power is needed for control valves and electronics).