Growing plants under microgravity conditions in a space ship is essential for future long term missions to supply needs for food and oxygen. Although plant growth modules for microgravity have been developed and tested for more than 40 years, many open questions remain. An important issue is caused by plants becoming waterlogged as fluid distributions under microgravity differ drastically from those on Earth. Rather than relying on gravitational forces to create suitable fluid distributions, this project proposes using porous media with patterned wettability characteristics to manipulate fluid saturation under microgravity conditions.
Various wettability patterns are examined in bead packs under microgravity conditions. Microgravity conditions for fluid flow in these experiments are created using density matched fluid pairs on Earth, representing the behaviour of water and air in space. Furthermore, the influence of grain shape on fluid distributions is investigated under Earth gravity by conducting spontaneous imbibition experiments in synthetic porous media as well as in common potting soil. Using state-of-the-art three dimensional computer tomography, fluid distributions are measured with a resolution on the order of μm.