The “Thermocapillary-based control of a free surface in microgravity” experiment

Present and future challenges of space exploration require better and improved strategies for fluid control and management. The “Thermocapillary-based control of a free surface in microgravity” (ThermoSlosh) experiment aims to contribute directly to current knowledge and basic understanding of fluid phenomena in reduced gravity, in particular, to study the effectiveness of thermal forcing for fluid control in weightlessness and applications. The experiment proposes to analyze the dynamics of a free surface in a cylindrical cell, half filled with 5 cSt silicone oil, subjected to controlled temperatures and accelerations. Simulations suggest that the thermocapillary effect can be used in microgravity to control the orientation of the free surface within the cell. The response of the free surface to the applied thermal gradient is characterized using the rise time, the stabilization time, and the overshoot; these representative quantities further help evaluating the effectiveness of the strategy. The use of supplemental vibrations is shown to improve the overall performance of the thermal control. Finally, among various potential applications, the ability to control sloshing motion during the real microgravity scenario of an ISS reboosting maneuver is assessed. ThermoSlosh was recently presented to the International Space Science and Scientific Payload competition, and is part of the selected proposals for the competition final.