Novel laser-based gas sensors for trace gas detection in a spacecraft habitat

INTRODUCTION Ammonia vapor is one of the nitrification by-products produced by a tubular bioreactor being developed at the NASA Johnson Space Center for wastewater treatment during long duration space missions (Figure 1). In order to quantify this NH3 vapor production, a portable diode laser-based gas sensor for NH3 detection using overtone infrared absorption spectroscopy was developed, and a 2-week campaign to carry out concentration measurements was performed. This sensor is capable of NH3 vapor concentration measurements at the parts-per-million (ppm) level in the bioreactors being developed by NASA-JSC for water recycling in the International Space Station. The use of all fiber-coupled optical components makes such a trace gas sensor rugged and alignment insensitive.