The speed of a crash landing on its surface is typically between 70 and 100% of the escape velocity of the target moon, and thus this is the total velocity which must be shed from the target moon’s gravitational attraction for a soft landing to occur. For Earth’s Moon, the escape velocity is 2. 38 kilometres per second (1. 48 mi/s). The change in velocity (referred to as a delta-v) is usually provided by a landing rocket, which must be carried into space by the original launch vehicle as part of the overall spacecraft. An exception is the soft moon landing on Titan carried out by the Huygens probe in 2005. As the moon with the thickest atmosphere, landings on Titan may be accomplished by using atmospheric entry techniques that are generally lighter in weight than a rocket with equivalent capability.
The "Dagwood Sandwich" Moon. Earlier models of Ganymede's oceans were based on the assumption that the existence of salt didn't change the nature of liquid very much with pressure. However, Dr. Vance and his colleagues found, through laboratory experiments, that salt does increase the density of liquids under the extreme conditions hidden deep within Ganymede and similar icy moons with subsurface bodies of water. Imagine adding table salt to a glass of water. Instead of increasing in volume, the liquid will actually shrink and become denser. The reason for this is that salt ions lure water molecules. The moon and fishing are forever tied together and you can learn what you need to know with nothing more than a little research. That's right folks, it won't cost you one red cent to learn the information that you need to know about the moon and fishing. All you have to do is invest a little bit of time and you'll be good to go. There's no need to take the equivalent of a college course on this subject, just a little time will do. During Cassini's close flyby of Enceladus on October 28, 2015, it detected molecular hydrogen as the spacecraft zipped through the plume of ice grains and gas spraying out from cracks slashing though the icy crust of the moon-world. Earlier flybys provided hints that a global subsurface ocean did, indeed, exist, sloshing around above a rocky core. Molecular hydrogen in the plumes could indicate hydrothermal processes, which could play the important role of providing the chemical energy so necessary to support life as we know it. In order to hunt for hydrogen specifically originating on Enceladus, the spacecraft dived particularly close to the strange slashed surface.