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An advanced trace gas monitoring system for long duration manned space missions - such as the International Space Station - is discussed. The system proposed is a combination of a Fourier-Transform Infrared Spectrometer (FTIR) and a distributed ‘Smart Gas Sensor system (SGS). In a running multi-phase programme [1,2] the FTIR technology, applying novel analysis methods, has been demonstrated to handle multi-component gas measurements, including identification and quantification of 20 important trace gases in a mixture. In the current phase 3, initiated end of 1997, a fully operational FTIR technology demonstration model will be manufactured and tested. The SGS consists of an array of twenty electrically conductive polymer sensors supplemented with an array of quartz crystal microbalance sensors. The technology has been tested on the Russian MIR space station and is currently miniaturized into a second-generation flight model.

In an earlier assessment of trace gas monitoring techniques it was shown that Fourier Transform Infrared Spectroscopy (FTIR) is the most promising technology for multicomponent gas analysis of the breathing air for long duration crewed space missions. It has the potential of meeting all the requirements established for the different trace gas monitoring scenarios; however, it needs further development. An important step to achieve this development objective is the breadboarding of such an FTIR system with particular emphasis on the critical technologies. The critical technologies as identified so far are the detector and cooler, the gas cell, the infrared source, and the analysis software. In this paper we will present and discuss the relevant requirements, the planned instrumental and software concept to be realized for meeting the intended monitoring task, and the expected performance data of the breadboard. The work is being performed under ESA contract.

This paper presents the results of the breadboarding study phase of a Fourier transform infrared spectrometer (FTIR) based trace gas monitor for the use on-board a manned spacecraft. The FTIR system configuration includes a multiple-reflection long path gas cell, a half-wavenumber resolution interferometer, and a mercury-cadmium-telluride (MCT) detector. In the study, the emphasis was put on the achievement of a predefined analytical performance using a state-of-the-art multivariate analysis method. Robustness of the employed algorithms was to the fore rather than a sophisticated FTIR instrumentation. The achieved results show high accuracy in detecting trace gases in the range between the (lower) long-term and (higher) short-term Spacecraft Maximum Allowable Concentration (SMAC) limits. The project has demonstrated a good proof-of-concept for the use of an FTIR system in manned space flights.