"Ganymede's ocean might be organized like a Dagwood sandwich," commented Dr. Steve Vance in a May 1, 2014 statement. Dr. Vance, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, went on to explain the weird moon's resemblance to the Blondie cartoon character's famous multi-layered sandwiches. The study, headed by Dr. Vance, provides new theoretical indications for the team's "club sandwich" model, originally proposed in 2013. The research appears in the journal Planetary and Space Science.
"From what we know about cloud formation on Titan, we can say that such methane clouds in this area and in this time of year are not physically possible. The convective methane clouds that can develop in this area and during this period of time would contain huge droplets and must be at a very high altitude--much higher than the 6 miles that modeling tells us the new features are located," Dr. Rodriguez explained in the September 24, 2018 JPL Press Release.
The astronomers observed this effect in the upper layer of the lunar crust, termed the megaregolith. This layer is heavily pockmarked by relatively small craters, measuring only 30 kilometers or less in diameter. In contrast, the deeper layers of lunar crust, that are scarred by larger craters, appear not to have been as badly battered, and are, therefore, less porous and fractured.