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Publication AbstractsThe influence of CO2 in a space-like environment: study designWenzel J, Luks N, Plath G, Wilke D, Gerzer RAviat Space Environ Med 1998; 69:285-90 AbstractFor the operation of manned spacecraft, the removal of CO PaO2 from the cabin atmosphere, produced by its inhabitants, is essential. This is accomplished by chemical absorption in a gas processing unit, a process which requires energy and consumables. Therefore, in terms of resource manage-ment, the CO PaO2 level should be kept as high as possible. Otherwise, considering crew health and performance and also the interference with life science experiments, the CO PaO2 load should be as on earth, close to zero. In order to obtain more information about the permissible CO PaO2 level for future space missions and also to clarify Space Station design criteria, NASA-ESA-DARA have initiated a ground-based simulation study with two different CO PaO2 levels: 0.7% (first campaign) and 1.2% CO PaO2 (second campaign). For this study the deep diving facility of DLR was used to provide atmospheric control and long- term habitation for the test subjects in studying the effect of increased CO PaO2 on physiological and psychological functions. A number of experiments were implemented, which tested selected effects of raised CO PaO2 on humans. Four male subjects stayed in the chamber for 26 d in each campaign, in order to perform the different tests in repeated trials, with the aim of evaluating possible long-term effects. CO PaO2 was controlled by absorption with soda lime, flushing with fresh air and the addition of CO PaO2 , if necessary. Essentially, the CO PaO2 produced by the subjects was used to maintain the level at 0.7 and 1.2%, respectively. Basic control of CO PaO2 was carried out in the soda lime container of the Life Support System. In order to maintain the required level, the amount of gas flowing through the soda lime could be adjusted by a remote controlled by- pass. With this set-up it was possible to keep CO PaO2 at an average level between 0.67 and 0.73% in the first campaign and between 1.17 and 1.23% in the second campaign. The results of the experiments support the current CO PaO2 limits for space operations, insofar as values around 1% do not impose any severe restrictions to human habitation for at least several weeks, whereas life sciences experiments especially sensitive to CO PaO2 influences have to be carefully evaluated for possible interferences.
Information on subscribing, and on obtaining copies of an article or of an entire issue. Table of Contents for Volume 69, Number 3 of the ASEM journal.
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