One of the most interesting studies was the CO2 study issued by the NASA. The elimination of CO2 from the atmosphere of the cabin is of utmost importance for the operation of a manned space station. This is accomplished by a life support system (LSS), the gas circulation of which chemically binds CO2. The CO2 is created by the respiration of the crew. Without elimination, it would add CO2 to the closed atmosphere, causing health damage. However, for a regeneration of the air, energy and consumables are needed. In order to save the narrow ressources, the CO2 level should be as high as possible. On the other hand, a level as low as possible (comparable to the earth atmosphere) would be perfect for the health and performance of the crew.
Different CO2 levels:
0.05 % >
0.5 % >
0.3 bis 1.5 %, lower technical limit 0.1%
For technical systems (e.g. submarines or buildings), concentrations between 0.1 % and 3 % of CO2 have been examined. CO2 levels between 0.3 % and 1.5 % are being discussed for space flights. In order to be able to gain more information about human performance under these CO2 levels for future missions, the NASA/ESA have commissioned an international ground-based study (several groups of scientists with different topics, e.g. cardiology, respiration physiology, psychology, motor function) at 0.7 % and 1.2 % from the DLR.
Although physiological reactions were registered, no significant changes in performance could be observed. A CO2 level of 1.2 % is thus possible in space travel without security reservations. On the other hand, with experiments in life science, the CO2 level has to be kept low enough to make a comparison with laboratory experiments on earth.
All experiments took place in the baro-chamber complex "TITAN", where good conditions for the measurement of the influence of different gas mixtures and/or isolation according to physiological and psychological parameters are given.