Jupiter's giant moon Ganymede may possess ice and oceans stacked up like a "club sandwich."
The moon is the largest in our solar system; it may have once held an ocean held between two layers of ice on top and bottom, a NASA Jet Propulsion Laboratory news release reported.
"Ganymede's ocean might be organized like a Dagwood sandwich," Steve Vance of NASA's Jet Propulsion Laboratory said in the news release.
New research suggests the icy moon may have been hospitable to primitive life. Where water and rock meet and interact help support the development of life, but in the past researchers believed Ganymede's sea floors were covered in ice; this would have made it almost impossible for life to pop up. This "sandwich" finding suggests otherwise.
"This is good news for Ganymede," Vance said. "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 sea floor."
NASA's 1990s Galileo mission found evidence of the moon's ocean, and the findings also suggested the presence of salt water. The researchers showed the salt increases the water's density because salt ions attract water molecules.
The researcher's model also showed a strange phenomenon that would cause the moon's oceans to "snow upwards." Ice in the uppermost layer of the ocean would form seawater, heavier salts would fall forwards while light ice and snow would float towards the surface. This upwards "snow" could create slush right in the center of the "sandwich."
"We don't know how long the Dagwood-sandwich structure would exist," Christophe Sotin of JPL said in the news release. "This structure represents a stable state, but various factors could mean the moon doesn't reach this stable state.
