In order to control the work of ensuring a given gas composition, to manage these means and evaluate the suitability of the atmosphere for the stay of astronauts, you need to have information about the current amount of each of those components that affect human life. This means that it is necessary to regularly analyze the chemical composition of the atmosphere. The frequency and methods of control for different components can be different, depending on the degree of their effect on the human body and the maximum possible speed of quantitative changes. Particular attention in the analysis is always paid to the measurement of partial pressure of oxygen, carbon dioxide and water vapor. This is due to the fact that these parameters are most dynamic, and therefore require almost continuous control. For its implementation, automatic gas analyzers are installed on board.