On the International Space Station (ISS), atmospheric humidity condensate and other waste waters will be recycled and treated to produce potable water for use by the crews. Space Station requirements include an on-orbit capability for real-time monitoring of key water quality parameters, such as total organic carbon (TOC), total inorganic carbon (TIC), total carbon (TC), pH, and conductivity, to ensure that crew health is protected during consumption of reclaimed water. The Crew Health Care System (CHeCS) for ISS includes an analyzer that has been designed to meet this requirement. The analyzer is adapted from commercially successful technology, and it measures TOC and TIC throughout the range from 1 to 50,000 μg/L, and TC from 1 to 100,000 μg/L. It measures pH between 2.0 and 12.0 pH units, and conductivity from 0.1 to 300 μmho/cm.
The analyzer is scheduled for launch to ISS on mission 2A.1. In preparation for use on ISS, an earlier version of the analyzer was successfully tested on Shuttle during the STS-81 mission as a Risk Mitigation Experiment (RME). Postflight inspection of the analyzer revealed that some design changes would be needed for improved reliability. Additional design changes were incorporated recently to increase the maintainability of the analyzer, improve analytical performance, and reduce operating costs. This paper summarizes those design changes and the results of tests performed to prepare the analyzer for use on the ISS.