Smectic Liquid Crystal Bubbles in Microgravity: Fluid Physics in Two Dimensions*

The Observation and Analysis of Smectic Islands in Space (OASIS) project comprises a series of experiments that probe the interfacial and hydrodynamic behavior of thin, spherical-bubbles of smectic liquid crystal in microgravity. In fluid smectic phases, each molecular layer is a two-dimensional (2D) liquid, with only short-ranged positional pair correlations within the layer planes and from layer to layer in the direction parallel to the layer planes. Such materials can be used to draw very thin films across an aperture and to blow bubbles. The resulting structures are extremely stable and are uniform in thickness, apart from pancake-like inclusions with additional smectic layers called islands. Smectic films are the thinnest known stable condensed phase structures, making them ideal for studies of 2D coarsening dynamics and thermocapillary phenomena in microgravity.
The OASIS flight hardware, developed in collaboration with NASA, was successfully launched on SpaceX-6 on April 15, 2015 and experiments were carried out on the International Space Station. We will describe the experimental hardware and present preliminary results from the OASIS experiments, where we investigated the equilibrium spatial organization, temperature gradient-induced themomigration, and the diffusion and coalescence-driven coarsening dynamics of island emulsions on smectic bubbles in microgravity.
The OASIS project was performed in collaboration with Noel A. Clark, Matthew A. Glaser, and Cheol S. Park (University of Colorado), Alexey Eremin, Kirsten Harth, Christoph Klopp, Ralf Stannarius, and Torsten Trittel (University of Magdeburg), Nancy Hall and Padetha Tin (NASA Glenn Research Center), and William N. Thurmes (Miyota Development Center of America).