Electrical Properties of Icy World Oceans from Laboratory Measurements

Many icy bodies harbor subsurface liquid-water oceans, with Jupiter’s moon Eu-ropa among the most promising for astrobiology. NASA’s Europa Clipper missionwill collect magnetic induction measurements to constrain Europa’s ocean compositionand thickness. Interpreting this information requires accurate electrical conductivitydata extending to the extreme conditions of composition, temperature, and pressurepossible in Europa’s ocean. Here we report systematic laboratory measurements ofelectrical conductivity for Europa-relevant brines (NaCl, MgSO4, NH4Cl, Na2CO3, andtheirmixtures)inthetemperaturerangefrom−10 ◦C to25 ◦C andconcentrationsupto150 g/kgH2O, at ambient pressure. The results reveal that the widely used1 model over-estimates conductivity by up to 15% at high concentrations and subzero temperatures,1with deviations large enough to cause misinterpretation of Europa Clipper magneticfield measurements. This project provides critical experimental constraints for inter-preting upcoming Europa Clipper data and enables stronger assessments of Europa’socean composition and potential to support life.