Portable Tunable Laser Spectrometer (PTLS) Technology Demonstration on the International Space Station: Performance and Reliability Before Launch and Science Objectives

The Portable Tunable Laser Spectrometer (PTLS) is an environmental monitoring sensor designed for human space exploration that measures carbon dioxide, water vapor, and oxygen. It is a collaborative effort between NASA Jet Propulsion Laboratory and Southwest Sciences Inc. (SWS). Six identical PTLS instruments have been manufactured and are scheduled to be deployed on the International Space Station (ISS) in mid to late 2025 as part of a multiyear technology demonstration. The system of PTLSs will be distributed around the U.S. Lab, interconnected and transmitting data to a central base station via a Zigbee wireless mesh network. Deployment includes assessing instrument and network performance, analyzing timeseries data as it pertains to crew health, and conducting focused experiments (during which the instruments will be relocated by crew) exercising the capabilities of the sensors. To ensure successful, safe on-orbit operation, we carried out design, manufacturing, and testing processes to meet stringent requirements and with great emphasis on crew interfacing, reliability, and system safety engineering principles.