Influence of Environment on Measurements Made on EVA or “Space Station Freedom”

A Portable Contamination/Leak Detector (PC/LD) is being developed for use by crew on Extravehicular Activity (EVA) to locate trace leaks from Space Station Freedom (SSF) systems and to monitor the surfaces of the Extravehicular Mobility Unit (EMU) for toxic contaminants being removed prior to ingress to the airlock. As with any trace level detector the background in which it operates has a significant impact on the operation and design of the instrument. The PC/LD operates in space vacuum and is sensitive to the composition and pressure which exists near the station.

This paper describes the PC/LD mission, some data on the composition of ambient space environment and implications of that data on the PC/LD's design and usage.