Design and Testing of a Water-Based Condensation Particle Counter for a Micro-Gravity Environment

STEVEN SPIELMAN, Gregory S. Lewis, Nathan Kreisberg, Susanne Hering, Aerosol Dynamics Inc.

     Abstract Number: 612
     Working Group: Instrumentation and Methods

Abstract
The International Space Station (ISS) provides an environment for a 6-member crew to live and work in low Earth orbit. As a completely sealed volume, maintaining good air quality is vitally important. While gas phase constituents of ISS air are monitored meticulously, NASA has focused on aerosols only recently. This work addresses the monitoring of submicron particles by using water condensational growth. The ISS environment introduces several challenges. First, no liquid reservoirs were permitted for this work and a fully dry system was required for launch acceptance. The working fluid must be gathered from the ambient air during sampling. Second, because the instrument cannot rely on gravity to shed excess water from the wick, the saturation level of the wick must be measured and controlled to prevent flooding. Third, the absence of any gravitational settling means the unit must tolerate 5 to 50 micron particles, which threaten to clog the optics nozzle. A virtual impactor was designed to handle the coarse particle load in a way that requires no disassembly by crew. Results showing the robustness against wick-drying events, along with overall system performance will be shared.