NASA’s Galileo spacecraft has provided conclusive evidence that Jupiter’s moon Callisto is an ocean world, with a subsurface liquid water ocean and a solid ice shell. In 1990s data analysis, magnetic measurements suggested the presence of a salty, conductive ocean beneath the icy surface. However, inconsistencies arose due to the moon’s intense ionosphere. Researchers have now revisited this data using advanced statistical techniques and computational models. Their findings reveal that Callisto’s ionosphere alone cannot explain all existing observations, but when combined with the subsurface ocean, it provides a strong case for its existence.
The new analysis incorporates all available magnetic measurements from eight close flybys of Callisto and suggests that the moon hosts a massive ocean at least tens of kilometers thick. This rocky interior is encased beneath a solid ice shell, which could be hundreds of kilometers thick. These findings pave the way for future spacecraft missions, including NASA’s Europa Clipper and JUICE missions, to confirm or refute Callisto’s status as an ocean world. The discovery also raises hopes for further research into its potential support for life.
Source: https://phys.org/news/2025-02-jupiter-moon-callisto-ocean-world.html