The distribution of trace contaminants in the manned space station atmosphere

• Published in: Acta astronautica 2022-12, Vol.201, p.597-601
• Main Authors: Moukhamedieva, L., Ozerov, D., Pakhomova, A.
• Format: Article
• Language: English
• Subjects: Air quality; Life support systems; Log-normal distribution; Space station; Trace contaminants
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2022.09.053

The research is based on the results of air quality monitoring for the period from 2000 to 2020. The air samples have been taken onboard the International Space Station (ISS) using AK-1M samplers and delivered to Earth. The representativeness of the research results is confirmed by the long-term duration (20 years of observation) and the amount of experimental data (analysis of more than 30,000 measured concentrations of chemicals identified by gas chromatography and mass spectrometry). Statistical analysis of measured concentrations showed that the vast majority (70%) of trace contaminants detected in the ISS air have a log-normal distribution, which is confirmed by the use of the Kolmogorov-Smirnov goodness-of-fit test (p > 0.2). For the remaining 30%, the significance level of the Kolmogorov-Smirnov goodness-of-fit criterion was less than 0.2, however, the statistical distributions of these trace contaminants are characterized by unimodality, peakedness (kurtosis coefficient significantly >2) and asymmetry (skewness coefficient >1) with a shift towards lower values, which regarded as a “close to normal distribution”. It has been established that the log-normal model can be accepted as a theoretical model describing the distribution of trace contaminants in the air of manned space stations. The established log-normal distribution and the ratio between the average concentrations of different averaging periods (10 : 3: 1.5 : 1) confirms the uneven nature of air pollutants in the modules and the possibility of the formation of “stagnant” zones. This is of great practical importance, which must be taken into account when establishing the air quality standards for trace contaminants and designing life support systems (ventilation and air purification) for manned space stations. •Log-normal distribution of trace contaminants in space station atmosphere.•Concentrations of trace contaminants have an extreme variability in time and space.•Total air pollution increases after docking.•Mathematical approaches to predict the level of air pollution.