Challenges remain for design engineers to produce robust fluids handling equipment for spacecraft such as critical life support systems: i.e., oxygen supply, air revitalization, thermal management systems, water reclamation, medical fluids, and others. The new passive phase separating components to be designed and developed in this Phase I effort can be exploited across a variety of spacecraft fluids systems to markedly increase system reliability and performance. They may also be employed throughout spacecraft in systems from fluid feed lines in hydrolysers, to condensing heat exchangers, urine processors, portable life support systems, plant and animal habitats, food preparation facilities, propellant management systems, and othersbasically, all liquid systems on spacecraft: coolants, water, aqueous solutions, fuels, and cryogens. The components offer the advantages of no moving parts, little to no pressure loss, and no additional power consumption, and could benefit greatly in terms of increased TRL via testing aboard the ISS. This research applies recent advances in the study of microgravity capillary flows and phenomena. We expect to change the overall approach to spacecraft fluid systems design and provide common geometries that naturally and routinely separate fluid phases in a manner more akin to terrestrial applications and experience. Our primary intent for low-gravity demonstration aboard the ISS is to increase TRL levels and gain wider acceptance for our non-traditional approach among the aerospace community. However, terrestrial applications are identified and pursued as part of our broader commercial objectives in Phase I and Phase II. Applications of our design approach to routine microfluidic flows relating to fuel delivery and biomedical drug delivery represent significant growth opportunities.