Spacecraft Water Impurity Monitor (SWIM), a System for Water Quality Analysis on Exploration Missions Beyond LEO

Exploration missions beyond low-earth-orbit (LEO) will require advanced instrumentation to monitor water quality. Traveling beyond LEO means the transfer of water samples to an Earth-based laboratory for detailed analysis is not possible. Detailed analysis of water composition during exploration is still necessary, because having the capability to determine the specific organic chemical causing a change in total organic carbon (TOC) or the specific metal or ionic species causing a change in conductivity has the potential to steer the crew health and system management decisions differently. On a new vehicle such as a lunar or Mars surface habitat or a Mars transit vehicle, the occasion of finding “new” impurities not seen on ISS should be expected. The key is to identify the impurity so the correct action can be taken. On ISS we can measure TOC, conductivity, and other physical properties but do not have the capability for detailed analysis using vehicle instrumentation. This is acceptable because ISS can send samples down to Earth for further analysis in a timely manner. For exploration, the inability to send samples to Earth is why SWIM is a necessary new technology suite. SWIM is the answer to detailed water quality analysis when sample down mass is not available. SWIM is a system comprising organic and inorganic modules. For organic chemicals, a gas chromatograph mass spectrometer (GCMS) detects and identifies organic impurities. For inorganic species, a capillary electrophoresis capacitively coupled contactless conductivity detection (CE-C4D) system as well as ion specific electrodes detect and identify metal ions and other inorganic salts / acids. The SWIM technology demonstration project is currently working to define requirements for an ISS technology demonstration of the organic and inorganic subsystems, while continuing to conduct technology feasibility and technology maturation efforts prior to beginning detailed system design for the flight instrument.