Tunable Laser Spectrometer for the Miniaturized Total Organic Carbon Analyzer

Tunable diode laser spectrometer (TLS) type instruments are widely used in trace gas sensing applications due to their selectivity, sensitivity and miniaturization capabilities. Here we present the design and environmental testing results for a new miniaturized tunable laser spectrometer designed to detect gas phase CO2 from the miniaturized total organic carbon analyzer (MiniTOCA) due to operate onboard the ISS as a technology demonstration starting 2026. The MiniTOCA Tunable Laser Spectrometer (MTLS) has NASA-defined Criticality-1R reliability design features (e.g. built in reference cell, redundant pressure sensors, specialized high-reliability hermeticity seals) that make it suitable for long term (years) deployment in human habitation structures. We have successfully built and validated three flight units as part of this study. We discuss design, calibration, and verification and validation of the instrument over a range of temperature, pressure, vibration and elevated CO2 tests, as well as operational temperature, pressure and high humidity tests. Miniaturized TLS instruments of this kind will be highly applicable to other gas phase sensors for Portable Life Support Systems (PLSS) and Life Support Systems (LSS) and could be adapted and repurposed for Earth and Planetary science applications where miniaturization and high-reliability is important for networks of sensors, drone flight and in-situ probe applications.