The open-source PlanetProfile framework was developed to investigate the interior structure of icy moons based on self-consistency and comparative planetology. The software, originally written in Matlab, relates observed and measured properties, assumptions such as the type of materials present, and laboratory equation-of-state data through geophysical and thermodynamic models to evaluate radial profiles of mechanical, thermodynamic, and electrical properties, as self-consistently as possible. We have created a Python version of PlanetProfile. In the process, we have made optimization improvements and added parallelization and parameter-space search features to utilize fast operation for investigating unresolved questions in planetary geophysics, in which many model inputs are poorly constrained. The Python version links to other scientific software packages, including for evaluating equation-of-state data, magnetic induction calculations, and seismic calculations. Physical models in PlanetProfile have been reconfigured to improve self-consistency and generate the most realistic relationships between properties. Here, we describe the software design and algorithms in detail, summarize models for major moons across the outer solar system, and discuss new inferences about the interior structure of several bodies. The high values and narrow uncertainty ranges reported for the axial moments of inertia for Callisto, Titan, and Io are difficult to reconcile with self-consistent models, requiring highly porous rock layers equivalent to incomplete differentiation for Callisto and Titan, and a high rock melt fraction for Io. This effect is even more pronounced with the more realistic models in the Python version. Radial profiles for each model and comparison to prior work are provided as Zenodo archives.

A key question pertaining to Europa’s habitability is whether hydrothermal activity could be sustained for long periods of time, enabling redox and nutrient exchange between the ocean and rocky interior [e.g. 1, 2]. Europa’s early ocean, if formed during differentiation, could have been infused with gases [3]. A consequence of this initial infusion is that clathrate hydrates may have been stable within the ocean. These clathrates could then rise to the bottom of the ice shell, or blanket the seafloor, depending on their density relative to the ocean. Accumulations of floating and sinking clathrates would affect the geological and thermal evolution of Europa because of their high heat capacity and low thermal conductivity compared to ice Ih, but sinking clathrates could also inhibit chemical exchange between the ocean and the rocky interior. We calculate the stability and density of CH4 and CO2 clathrates, and predict the volumes precipitated at the seafloor or accumulated at the base of the ice shell, for ocean compositions evolved from the interior of Europa during metamorphism on the path towards formation of a metallic core [3]. For a chemically reduced ocean derived from heating a mix of chondritic material near Jupiter [4], plus cometary volatiles, ~2 x 10^7 km^3 of methane clathrates form. These are less dense than the ocean (Fig. 1), and float to the base of the ice shell. However, for a CO2-rich ocean derived from CI or CM chondrites, ~3 x 10^8 – 2 x 10^9 km^3 of CO2 clathrates could form, i.e., sufficient feedstock to form a 13–77 km global layer on the seafloor. A salty ocean (e.g. 10 % MgSO4) or a warm seafloor (316 K) may be needed to prevent the accumulation of a CO2 clathrate blanket (Fig. 1), although the blanketing effect would thin the equilibrium thickness of the clathrate layer to ~500 m for allowable heat fluxes (~50 mW/m^2). [1] Vance, S. et al. (2007). Astrobiology, 7(6), 987–1005. https://doi.org/10.1089/ast.2007.0075 [2] Klimczak, C. et al. (2019). 50th Lunar. Planet Sci. Conf., Abstract #2132, p. 2912. https://ui.adsabs.harvard.edu/abs/2019LPI….50.2912K [3] Melwani Daswani, M. et al. (2021). A metamorphic origin for Europa’s ocean (preprint). https://doi.org/10.1002/essoar.10507048.1 [4] Desch, S. J. et al. (2018). Astrophys. J., Suppl. Ser., 238(1), 11. http://dx.doi.org/10.3847/1538-4365/aad95f

A seismic investigation on Saturn’s moon Enceladus could determine the thickness of the ice shell, along with variations from the mean thickness, by recovering phase and group velocities, and through the frequency content of surface waves. Here, we model the Enceladus ice shell with uniform thicknesses of 5 km, 20 km, and 40 km, as well as with ice topography ranging from 5-40 km. We investigate several approaches for recovering the mean ice shell thickness. We show that surface wave dispersions could be used to determine the mean ice shell thickness. Flexural waves in the ice only occur if the shell is thinner than a critical value < 20 km. Rayleigh waves dominate only in thicker ice shells. The frequency content of Crary waves depends on the ice shell thickness.

Computational software for planetary science and astrobiology is vital for understanding how complex systems interact, and for the analysis of sparse spacecraft data. PlanetProfile is an open source framework for modeling the interior of planetary bodies, especially ocean worlds, and is available in Matlab. We have rebuilt PlanetProfile in Python to improve its accessibility, as Python is free and widely used in scientific computing. PlanetProfile features such as the calculation of induced magnetic fields and seismic properties permit wider availability of these important tools for research purposes. An upcoming release of PlanetProfile contains the converted and streamlined software. New features such as a graphical user interface are in development that will support new users in taking advantage of these valuable tools.

Europa likely has an active surface ice shell producing numerous low-magnitude (

Here we explore the detection limits of a seismic event originating from Europa’s silicate interior. Such an event could be used to constrain the tectonic regime, rheology, and internal dynamics of Europa’s deep interior. We use PlanetProfile to generate interior structure models of Europa with ice shell ranging from 5-50 km in thickness. We then use the models as inputs for AxiSEM and InstaSeis to generate a database of seismograms. Realistic noise is added using the approach of Panning et al. 2018. We show that a deep event (depth 155km) would produce seismic signals 1/10- 1/75 the amplitude of shallow (depth 3km) events. Thinner ice shells allow for more ground motion, and thus, a seismometer could detect a smaller magnitude event than if the ice shell was thick. A Mw 3.5 could overcome background noise, but a Mw 4.5 or greater is necessary to be detectable by even the most sensitive seismic instrumentation. A Mw 5.0 or greater is likely needed to be seen by a seismometer on Europa’s surface. Constraining deep seismicity would allow for better constraints on the deep internal structure and dynamics of Europa.