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Through the last decade ESA (European Space Agency) have developed a TGM (Trace Gas Monitoring) system for spacecraft air analysis from paper study to a fully operational breadboard [1–9]. The TGM system is a combination of FTIR spectrometry and specially developed analysis techniques. Ongoing work aims at a system flight experiment on e.g. the Space Shuttle early in 2003 [10]. This paper mainly covers the application of the TGM breadboard for a competitive blind testing on unknown multi-gas mixtures arranged by NASA. The TGM HW was applied as is, but a special calibration for the NASA test scenario was made. Four different system suppliers competed in the testing, and the ESA TGM system performed clearly best [11]. This independently defined and supervised testing has confirmed that the ESA TGM system is reliable to perform quasi-real time gas measurements in the concentration ranges required by ESA.

This paper presents the status of ongoing BB studies for an optimized trace gas monitoring (TGM) system configured to simultaneously and quasi-online detect (quantitatively and qualitatively) 30 different trace gases in manned spacecraft. The system principle relies on the detection of molecule absorption lines in the infrared being converted into a measured spectrum by a Fourier Transform Infrared (FTIR) Spectrometer. The work is based on 10 years study phases aiming now towards performance demonstration on unknown gas mixtures and an in-flight demonstration on Space Shuttle or ISS. The theoretical background, sensor combinations, SW principle descriptions and multi-module monitoring strategies have been reported earlier (please refer to reference [1] - [4], [6]).

In this paper, an advanced trace gas monitoring system for manned space cabins is presented. The principle of functioning of the measurement system is based on the detection of gas-specific absorption features in the Infrared area of the spectrum. The core element in the monitoring system is a Fourier-Transform Infrared (FTIR) Spectrometer. When calibration is carried out applying sophisticated, novel analysis methods, the system can simultaneously detect and quantify all the interesting gases in manned space cabins. In a previous Trace Gas Monitoring multi-phase program (TGM 2) [1],[2], the FTIR technology has demonstrated its ability to handle multi-component, quasi on-line gas measurements, including identification and quantification of 23 important trace gases in a mixture. In the ongoing phase 3 (TGM 3), initiated end of 1997 [3], a fully operational FTIR technology demonstration model is tested being able to detect simultaneously 30 different trace gases in a mixture.

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.

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.