NASA Discovers Jupiter's Giant Moon Ganymede Has 'Club Sandwich' of Oceans and Ice

First Posted: May 02, 2014 07:23 AM EDT

NASA scientists are learning a bit more about the largest moon in our solar system, Ganymede. They've discovered that Jupiter's moon may have ice and oceans stacked up in several layers like a club sandwich. The findings reveal a bit more about the moon's structure, which may just help with further research.

Before now, scientists thought that the moon had a thick ocean sandwiched between just two layers of ice. Now, it seems that there may be more than just one of these layers.

"Ganymede's ocean might be organized like a Dagwood sandwich," said Steve Vance of NASA's Jet Propulsion Laboratory, in a news release.

How exactly did researchers discover this unusual structure? The scientists took Ganymede's ocean and ice into account and modeled them on computers. The researchers showed through laboratory experiments that salt increase the density of liquids under the extreme conditions inside Ganymede. They then used models to show that ice would become more compact under the crushing pressures on the moon. Using further models, the scientists were able to show that the ocean is probably sandwiched between up to three ice layers, in addition to the rocky seafloor. The lightest ice is on top, and the saltiest liquid is heavy enough to sink to the bottom.

"This is good news to Ganymede," said Vance in a news release. "Its ocean is huge, with enormous pressures, so it was thought that dense ice had to form at the bottom of the ocean. When we added salts to our models, we came up with liquids dense enough to sink to the seafloor."

In fact, the results reveal that primitive life might have actually arisen on the moon. The places where water and rock interact are important for life, and the fact that Ganymede's rocky sea bottom is not coated with ice could mean that there is the possibility for life.

The findings don't just have implications for Ganymede, though. They also have implications for exoplanets. Some exoplanets, called super-Earths, are thought to be "water worlds" covered in oceans. By learning all they can about Ganymede, the researchers can then apply their findings to other worlds.

The findings are published in the journal Planetary and Space Science.

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