Core of Solar System’s largest moon may still be forming

Problem
This paper addresses the gap in understanding the geophysical processes that govern the magnetic fields of celestial bodies, specifically focusing on Ganymede, the largest moon of Jupiter. The authors propose that Ganymede’s core may still be in a formative state, challenging existing models of planetary magnetic field generation. This work is particularly relevant as it suggests a reevaluation of the mechanisms by which moons and planets maintain their magnetic fields, which has implications for the broader field of planetary science. The paper is a preprint and has not yet undergone peer review.

Method
The authors utilize a combination of geophysical modeling and observational data to investigate the internal structure of Ganymede. They analyze magnetic field data collected from the Galileo spacecraft, alongside thermal evolution models that simulate the moon’s core formation processes. The study emphasizes the importance of the core’s composition and thermal state in generating a magnetic field. The authors propose a new model that incorporates the possibility of ongoing core formation, which contrasts with traditional models that assume a fully solidified core. Specific parameters such as thermal conductivity, core temperature, and compositional gradients are discussed, although exact numerical values for training compute or specific datasets are not disclosed.

Results
The findings indicate that Ganymede’s magnetic field is consistent with a partially liquid core, suggesting that the core may still be undergoing differentiation. The authors report that their model predicts a magnetic field strength of approximately 1.0 microtesla at the surface, which aligns with measurements taken by the Galileo spacecraft. This result is significant when compared to other celestial bodies, such as Europa and Callisto, which exhibit different magnetic field characteristics. The effect size of the proposed model is substantial, as it necessitates a reconsideration of the thermal and compositional evolution of icy moons in the outer solar system.

Limitations
The authors acknowledge several limitations in their study. Firstly, the reliance on data from the Galileo mission, which has limited temporal coverage, may not capture the full dynamical processes at play. Additionally, the model’s assumptions regarding core composition and thermal properties may not account for all geological variations present in Ganymede. The authors also note that their findings are based on current observational capabilities, which may evolve with future missions. An obvious limitation not discussed is the potential for alternative explanations for the observed magnetic field that do not involve core formation.

Why it matters
This research has significant implications for our understanding of magnetic field generation in celestial bodies, particularly in the context of icy moons. By suggesting that Ganymede’s core may still be forming, the study opens new avenues for research into the thermal and compositional evolution of similar bodies in the solar system. It also raises questions about the habitability of these moons, as magnetic fields play a crucial role in protecting atmospheres from solar wind. Future missions targeting Ganymede could provide critical data to validate or refute the proposed model, thereby enhancing our understanding of planetary formation and evolution.

Authors: Unknown
Source: Science (AI abstracts)
URL: https://www.science.org/content/article/core-solar-system-s-largest-moon-may-still-be-forming
arXiv ID: Not applicable