Understanding the interior structures of icy moons is pivotal for addressing their origins and habitability. We introduce an approach employing the gravity field spectrum as an additional constraint for the inversion of differentiated icy bodies’ interior structures. After developing the general methodology, we apply it to Europa, utilizing the predicted measurement capability of NASA’s Europa Clipper mission, and we prove its effectiveness in resolving key geophysical parameters. Notably, we show that using the gravity field spectrum in combination with the mass and moment of inertia of the body allows us to estimate, depending on the considered end-member interior structure, the hydrosphere thickness with 4–20 km uncertainty and reliably determine the seafloor maximum topographic range and elastic thickness to within 100–600 m and 5–15 km, respectively, together with the power–degree relationship of the seafloor topography. We also show that the proposed method allows us to determine the density of the silicate mantle and the radius of the core to within 0.25 g cc⁻¹ and 50 km, respectively.

中文翻译：

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利用重力场谱确定冰卫星内部结构：以木卫二和木卫二快艇任务为例

了解冰卫星的内部结构对于解决其起源和宜居性至关重要。我们介绍了一种利用重力场谱作为反演差异化冰体内部结构的附加约束的方法。在开发出通用方法之后，我们将其应用于木卫二，利用美国宇航局木卫二快艇任务的预测测量能力，并证明了其在解析关键地球物理参数方面的有效性。值得注意的是，我们表明，使用重力场谱与物体的质量和惯性矩相结合，使我们能够根据所考虑的端构件内部结构来估计具有 4-20 km 不确定性的水圈厚度，并可靠地确定海底最大地形范围和弹性厚度分别在 100-600 m 和 5-15 km 范围内，以及海底地形的功率-度关系。^{我们还表明，所提出的方法使我们能够分别在 0.25 g cc -1}和 50 km范围内确定硅酸盐地幔的密度和核的半径。