Jupiter’s Ganymede, the largest moon in our solar system, may contain ice and oceans, and possibly even life forms, stacked on top of each other like a “club sandwich,” NASA says.
Scientists previously believed that Ganymede was blanketed in a thick ocean sandwiched between two layers of ice. But now NASA says it believes there are more layers of ice and ocean covering the large satellite.
“Ganymede’s ocean might be organized like a Dagwood sandwich,” said Steve Vance of NASA’s Jet Propulsion Laboratory in Pasadena, California, a reference to the tall, multi-layered sandwiches enjoyed by Dagwood Bumstead, one of the protagonists in the popular “Blondie” comic strip.
The results of a study led by Vance conclude that it’s possible that life existed or exists on the icy moon. The interaction of water and rock is believed to be essential for the development of life, and life on earth may have evolved from bubbling vents on our ocean floors.
Before discovering the extra layers, scientists were skeptical that any life could have evolved on Ganymede because it was believed the moon’s sea bed was coated in ice, not liquid water. But the “club sandwich” hypothesis posits that salty water forms the bottom layer of the “sandwich,” greatly increasing the possibility that life exists or once existed on Ganymede.
“This is good news for Ganymede,” said Vance. “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 researchers have suspected the presence of water on Ganymede since the 1970s. Two decades later, NASA’s Galileo probe flew by the moon, confirming the existence of an ocean with an incredible depth of hundreds of miles. Evidence of salt water was also found.
Europa, another of Jupiter’s moons, was recently found to be spewing geysers of what appears to be matter originating from subsurface seas. NASA believes that it’s not unimaginable that there might be fish down in those waters. While NASA wants to send a probe to explore Europa, its proximity to Jupiter would leave spacecraft open to radiation damage unless expensive shielding is added.
NASA estimates it would cost anywhere from $2 billion to $4.7 billion to launch a viable Europa probe, and President Barack Obama’s 2015 budget request includes just $15 million for studying a possible mission to the sea-covered satellite.