2019-06-212019-06-212019-07-07ICES_2019_315https://hdl.handle.net/2346/84513Phillip Hicks, Jacobs Technology, USAJason Nelson, National Aeronautics and Space Administration (NASA), USAMichael Callahan, National Aeronautics and Space Administration (NASA), USAICES205: Advanced Life Support Sensor and Control TechnologyThe 49th International Conference on Environmental Systems as held in Boston, Massachusetts, USA on 07 July 2019 through 11 July 2019.Ionic silver is currently baselined as the biocide for microbial control in potable water systems for future space exploration missions. In-line monitoring of silver ion concentration is desired for system feedback control to introduce and maintain sufficient and safe levels of biocide in the water. To date, NASA testing of silver biocide system prototypes has made use of an Ion-Selective Electrode (ISE) for in-line silver concentration measurements. However, known issues with ISE technology have continued to motivate a search for alternate sensor systems. Although devices capable of detecting silver are available for terrestrial applications, these systems are generally not well-suited for the unique demands of spaceflight. Desired attributes include: low weight, volume, and power consumption; stable, autonomous, and in-line measurement capability; long calibration lifetime; and limited maintenance requirements. This paper provides the results from a preliminary trade study conducted on three candidate silver sensor technologies: ISEs, Anodic Stripping Voltammetry (ASV), and Fiber Optic Chemical Sensors (FOCS). The review of these technologies includes the rationale for their selection, an overview of the principles of their operation, and a detailed assessment of their strengths and weaknesses relative to the anticipated requirements of future spacecraft applications. The study concluded that none of the currently-available versions of these technologies is suitable for immediate application to spacecraft systems; further technology development should be considered. To that end, recommendations for forward development work have been proposed and provided herein.application/pdfengionic silverin-line sensingspacecrafttrade studyISEion-selective electrodeASVanodic stripping voltammetryFOCSfiber optic chemical sensoroptical sensorPresentations