Measurement of porous media hydraulic properties during parabolic flight induced microgravity

Bioregenerative life-support systems proposed for long-duration space missions require an understanding of the physical processes that govern distribution and transport of fluids in particulate porous plant-growth media. Our objectives were to develop hardware and instrumentation to measure porous-medium water retention and hydraulic transport properties during parabolic-flight induced microgravity. Automated measurements complimented periodic manual operations in three separate experiments using porous ceramic aggregates and glass beads. The water content was adjusted in multiple steps in periods of 1.8g. Continuous hydraulic potential measurements provided information on water retention. The short duration of microgravity limited the occurrence of equilibrium potentials under partially saturated conditions. Measured pressure gradients under fixed flow rates were largely unaffected by gravity force in saturated cylindrical porous-medium-filled flow cells. High resolution video imagery provided details on water imbibition rates into dry and previously wetted porous media. Additional analysis of these data will provide insight into the effects of reduced gravity on porous medium hydraulic properties.