Origin and diversity among the large icy moons: Ganymede, Callisto and Titan

2015 Fiscal Year Final Research Report

• Project/Area Number: 25800242
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Solid earth and planetary physics
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Kimura Jun 東京工業大学, 地球生命研究所, EON研究員 (00536138)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 氷衛星

Outline of Final Research Achievements

To explain diverse characteristics of surface and interior among three large icy moons, we constructed a new evolutional model considering the primordial hydrous core. In Ganymede, having largest radius and bulk density, decay energy of the long-lived radioactive elements heats the hydrous core, then deeper part of the core should be dehydrated and its viscosity became larger. Eventually the temperature of deeper core exceeds the eutectic of the metallic components, which means the metallic core can be formed. Dehydrated water would be risen up and large expansion and extensional tectonics must be occurred.
In Callisto, having little smaller radius and density than Ganymede, dehydration of the hydrous core would be insufficient and large metallic core could not be formed. Titan has an intermediate radius and density between Ganymede and Callisto, and dehydration of the hydrous core and metallic core formation can be occurred though its amount would be smaller than Ganymede.

Free Research Field

惑星科学