Exploring Callisto: Jupiter’s Ocean World Waiting to be Unveiled

Callisto is one of Jupiter’s moons, known for being the most cratered object in our solar system. While it seems geologically quiet, scientists have long suspected it might house a hidden ocean beneath its icy surface.

This idea gained traction in the 1990s when NASA’s Galileo spacecraft collected magnetic data suggesting a salty ocean could exist under Callisto’s icy shell, similar to Europa, another one of Jupiter’s moons. However, earlier evidence was complicated by the moon’s strong ionosphere, which could confuse the magnetic signals.

Recently, researchers took another look at the Galileo data, analyzing it more comprehensively than before. They included all available magnetic measurements from Galileo’s eight close encounters with Callisto. Their findings support the idea that an ocean lies beneath the surface.

The study, published in the journal AGU Advances, used advanced statistical methods and models of Callisto’s ionosphere to assess the situation. They found that the ionosphere alone couldn’t explain the observations. However, combining it with the presence of a subsurface ocean made sense of the data.

The team believes this hidden ocean could be at least tens of kilometers deep beneath an ice shell that might be dozens or even hundreds of kilometers thick. Below that, there’s likely a rocky core.

These discoveries pave the way for future missions, like NASA’s Europa Clipper and the European Space Agency’s JUICE mission. Both of these spacecraft have already been launched and will take close-up measurements of Callisto. There’s also a possibility that China’s upcoming Tianwen-4 mission will observe the moon.

If confirmed, Callisto’s status as an ocean world could spark new interest in its potential to support life, much like the excitement that followed similar findings about Europa.

For more details, check out the full study by Corey J. Cochrane and others titled “Stronger Evidence of a Subsurface Ocean Within Callisto” in the journal AGU Advances.

This information is shared from Eos, a product of the American Geophysical Union. You can read the original story here.