5:15 PM - 6:30 PM
[MIS14-P12] Viscosity of aqueous MgSO4 solutions at high-pressure and low-temperature: implications for icy satellites
Keywords:Icy satellites, Subsurface ocean, Viscosity, Aqueous magnesium sulfate solution, Diamond anvil cell
Some icy satellites, such as Europa, Ganymede, Enceladus, and Titan, have a subsurface ocean under the thick crusts. Though transport properties are essential to discuss the fluid behavior in these subsurface oceans, there are few viscosity data within P-T conditions corresponding to the ocean. Because fluid viscosity is dependent on temperature, pressure, and concentration, understanding these relationships leads to a more accurate view of the subsurface ocean.
The viscosity data of 10 wt% aqueous magnesium sulfate solutions were measured using a diamond anvil cell (DAC). The solutions' viscosity was determined up to 1100 MPa in the temperature range from −10 to 40°C from the falling sphere measurements with DAC by constructing apparatus with a rotating stage, microscope, and camera. The pressure was measured using the ruby fluorescence method (Piermarini et al., 1975), while the temperature was controlled by flowing cooling or warming water through the DAC. The obtained viscosity was in the range of 1–10 mPa s and showed high pressure dependence of viscosity as well as temperature-dependence. Assuming that the subsurface ocean is composed of 10 wt% magnesium sulfate and satisfies the high-pressure and low-temperature conditions of the ocean, the ocean's dynamic viscosity would be in the range from 1 to 10 mPa s in the pressure condition below 700 MPa, which is higher than the viscosity of Earth's seawater. Because viscosity affects convection, diffusion rate, chemical reaction rate, and flowing velocity through the seafloor, this property might change the predicted habitability and oceanic composition.
The viscosity data of 10 wt% aqueous magnesium sulfate solutions were measured using a diamond anvil cell (DAC). The solutions' viscosity was determined up to 1100 MPa in the temperature range from −10 to 40°C from the falling sphere measurements with DAC by constructing apparatus with a rotating stage, microscope, and camera. The pressure was measured using the ruby fluorescence method (Piermarini et al., 1975), while the temperature was controlled by flowing cooling or warming water through the DAC. The obtained viscosity was in the range of 1–10 mPa s and showed high pressure dependence of viscosity as well as temperature-dependence. Assuming that the subsurface ocean is composed of 10 wt% magnesium sulfate and satisfies the high-pressure and low-temperature conditions of the ocean, the ocean's dynamic viscosity would be in the range from 1 to 10 mPa s in the pressure condition below 700 MPa, which is higher than the viscosity of Earth's seawater. Because viscosity affects convection, diffusion rate, chemical reaction rate, and flowing velocity through the seafloor, this property might change the predicted habitability and oceanic composition.