Ganymede: Ganymede is both the largest moon of Jupiter, our Solar System's planetary behemoth, as well as the largest moon in our entire Solar system. Observations of Ganymede by the HST in 2015 suggested the existence of a subsurface saline ocean. This is because patterns in auroral belts and rocking of the magnetic field hinted at the presence of an ocean. It is estimated to be approximately 100 kilometers deep with a surface situated below a crust of 150 kilometers.
Unfortunately, the various economic troubles which are plaguing Europe has caused ESA to spend less money than before, so many space programs in Europe has halted. However, both in China as well as in India, there are several ambitious programs present, which may cause any one of these nations to send another man to the moon in the next decade. Naturally, only time will tell; but nothing will change the fact that mankind's future is in the stars.
For those craters smaller than 30 kilometers in diameter, he discovered impacts both increased and decreased porosity in the upper layer of the lunar crust.