NASA scientists says that the largest moon in the solar system may harbor life in its inner oceans. Previously, scientists thought Ganymede only had one ocean between two ice layers, but data reveals that its structure is “ice and oceans stacked up in several layers like a club sandwich.”

According to Steve Vance—the lead paper author from NASA’s Jet Propulsion Laboratory in Pasadena, California—”this is good news for Ganymede. 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 says that the layers of Jupiter’s moon “supports the idea that primitive life might have possibly arisen on the icy moon. Scientists say that places where water and rock interact are important for the development of life; for example, it’s possible life began on Earth in bubbling vents on our sea floor. Prior to the new study, Ganymede’s rocky sea bottom was thought to be coated with ice, not liquid — a problem for the emergence of life. The “club sandwich” findings suggest otherwise: the first layer on top of the rocky core might be salty water.”

So good news for Ganymede indeed. Even better: According to the study, this may be common to other icy moons with large oceans.

Did You Know? Ganymede is one of five moons in our solar system thought to support vast oceans beneath icy crusts. The other moons are Jupiter’s Europa and Callisto and Saturn’s Titan and Enceladus. The European Space Agency is developing a space mission, called JUpiter ICy moons Explorer or JUICE, to visit Europa, Callisto and Ganymede in the 2030s. NASA and JPL are contributing to three instruments on the mission, which is scheduled to launch in 2022.