Compact spectroscopic sensor for air quality monitoring in spacecrafts

The air quality of any manned spacecraft needs to be continuously monitored in order to safeguard the health of the crew. Any fire event, accidental release of harmful gaseous contaminants or a malfunction in the air revitalization system has to be detected as fast as possible to provide enough time for the crew to react. In this paper, a fast sensor system based on laser spectroscopy is presented, which is able to detect three important gases: carbon monoxide for fire detection, hydrogen chloride for fire characterization and oxygen to monitor the air vitalization system. To provide a long maintenance-free operation time without the need for any consumables except power, a calibration-free measurement method was developed, which is only based on molecule specific constants which are available from the molecular data base HITRAN. The presented sensor offers the possibility for reliable and crosssensitivity-free air quality monitoring over a large pressure and temperature range.