"For the smallest craters that we're looking at, we think we're starting to see where the Moon has gone through so much fracturing that it gets to a point where the porosity of the crust just stays at some constant level. You can keep impacting it and you'll hit regions where you'll increase porosity here and decrease it there, but on average it stays constant," Dr. Soderblom continued to explain to the press on September 10, 2015.
Titan orbits Saturn once every 15 days and 22 hours. Like Earth's large Moon, in addition to many other moons in our Solar System, Titan's rotational period is precisely the same as its orbital period. This means that Titan only shows one face to its parent-planet, while the other face is always turned away.
"The near-side of the Moon has been studied for centuries, and yet continues to offer up surprises for scientists with the right tools. We interpret the gravity anomalies discovered by GRAIL as part of the lunar magma plumbing system--the conduits that fed lava to the surface during ancient volcanic eruptions," Dr. Maria Zuber explained in an October 1, 2014 NASA Press Release. Dr. Zuber is from the Massachusetts Institute of Technology (MIT) in Cambridge.