Jupiter's largest moon Ganymede may have ice and seas layered on top of each other like a "club sandwich," NASA says.
Researchers once thought that the moon, the largest in the solar system, had one thick ocean sandwiched between only two layers of ice.
Urgent: Do You Approve Or Disapprove of President Obama's Job Performance? Vote Now in Urgent Poll
"Ganymede's ocean might be organized like a Dagwood sandwich,"
Steve Vance of NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement. Ganymede is three-quarters the size of Mars and would be classified as its own planet if it revolved around the sun instead of Jupiter.
The "club sandwich" idea was first proposed last year and NASA said that the study "provides new theoretical evidence" for it. It also opens the door that primitive life may be on the moon because of the presence of water, NASA noted.
"This is good news for Ganymede," Vance said in the statement. "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."
The spacecraft Galileo first confirmed that the moon had water during a flyby in the 1990s, with oceans that extended to depths of hundreds of miles. Galileo found evidence of salty seas, likely containing magnesium sulfate, in the water as well.
A European space mission called JUICE, short for Jupiter Icy Moons Explorer, is scheduled to take off in 2022 to get a closer view of Ganymede along with Jupiter moons Europa and Callisto in the 2030s, giving Earth-bound researchers its best look at the "club sandwich" theory.
Scientists have long looked for planets with water on them inside and outside the solar system, seeing it as the first clue to possible alien life.
NASA plans to launch its own mission to Europa in the mid-2020s in search of water and alien life.
"Europa is a very challenging mission operating in a really high radiation environment, and there's lots to do to prepare for it,"
Beth Robinson, NASA's chief financial officer, told reporters in March, according to Space.com.
Urgent: Assess Your Heart Attack Risk in Minutes. Click Here.
Related Stories: