The 2013-2022 NASA decadal survey states that it is "
crucial [to develop] an inventory and isotopic composition of lunar polar volatile deposits to understand their emplacement and origin, modeling conditions and processing occurring in permanently-shadowed areas of the Moon and Mercury...". One of the most important volatiles to study is H2O as it has been found throughout the solar system and is thus centrally important for performing comparative planetology to understand the origin and evolution of the planets and their moons. In the case of the Moon, the recent discoveries of large H2O deposits near its surface enable the possibility of performing high-resolution, in-situ measurements of H2O isotope ratios in the near future with the appropriate technology. Given the high likelihood that at least one of the New Frontiers Missions of this coming decade will explore the moon, as suggested in the new NASA Decadal Survey, an instrument that can make these challenging measurements is highly relevant. Conventional technologies (e.g., isotope ratio mass spectrometry) cannot be readily deployed and require extensive consumables, making them impractical in meeting NASA's mission needs. Thus, new instrumentation is required that can accurately measure water isotopes (Delta_D, Delta_18O, and Delta_17O). Our proposed instrument will be an ideal candidate for exploring the Moon and other icy extraplanetary locations (e.g., Mars, Europa, Enceladus, comets). Besides its application to NASA, a compact, ultrasensitive water-isotope analyzer also has significant commercial applications for environmental research and medical diagnostics. A preliminary market analysis suggests 5-year revenue exceeding $8 14M for these two markets alone. The proposed work is essential in making these instruments more compact, rugged, and cost-competitive, and will thus enlarge the potential market size significantly.