Evaluation of a Portable Carbon Dioxide Monitor for Use Aboard the International Space Station

The crew of flight 2A.1 that manned the International Space Station (ISS) assembly mission (STS-96) in May 1999 experienced symptoms that they attributed to poor air quality while working in the ISS modules. Some of these symptoms suggested that an accumulation of carbon dioxide (CO₂) in the work area could have contributed to temporary health impacts on the crew. Currently, a fixed-position CO₂ monitor in the FGB is the only means of measuring this air contaminant aboard ISS. As a result of this incident, NASA directed the Toxicology Laboratory at Johnson Space Center (JSC) to deliver a portable CO₂ monitor for the next ISS assembly mission (STS-101).

The Toxicology Laboratory developed performance requirements for a CO₂ monitor and surveyed available CO₂ monitoring technologies. The selected portable CO₂ monitor uses nondispersive infrared spectroscopy for detection. This paper describes this instrument, its operation, and presents the results from ground-based performance testing.