Abstract The Galilean satellite Europa is a primary candidate for the study of ocean worlds. In anticipation of NASA's Europa Clipper and ESA's JUICE missions, we revisit the magnetic field measurements of the Galileo spacecraft. The ocean's induction response is governed by its induction amplitude and phase shift, which are a function of the ocean properties, i.e., its depth, thickness, and electrical conductivity. While prior work focused on deriving values for the former two by a qualitative comparison with measurements, this work emphasizes the characterization of Europa's ocean properties directly, including their uncertainties. For that, we perform an inversion of magnetic field measurements. Our model includes magnetic field contributions due to Europa's plasma interaction and the inhomogeneous field of Jupiter's magnetospheric plasma. We estimate the uncertainties of our plasma interaction model, our background field model, and the inducing field. Employing a chi‐squared analysis, we utilize these uncertainties to quantify the ocean properties and their uncertainties. We apply this method to the E14 flyby, which is currently the best flyby for such an inversion. Using existing depth constraints from the literature, we find a minimum conductivity of 1.6 S/m at 20 km depth and 2.8 S/m at 35 km depth. At the derived maximum depth, 49 km, the required conductivity exceeds current estimates. Our work is a first step for the development of methods which quantitatively constrain the various magnetic field contributions around Europa in future measurements, including their uncertainties, and highlights the challenges of a quantitative characterization using magnetic sounding.
Winkenstern et al. (2025) studied this question.