The astronomers then conducted an analysis called a Bouger correction in order to subtract the gravitational effect of topological features, such as valleys and mountains, from the total gravity field. What is then left is the gravity field hidden beneath the lunar surface, existing within its crust.
Now, the fishing magazines and sites around the Internet will have you believe that the relationship between solar/lunar cycles and fishing is much more complex than I have explained here. In reality it's not. In fact, if you try to follow most of the charts out there, you will find no direct correlation between those charts and the number and size of fish you catch.
The twin spacecraft flew in an almost-circular orbit until the mission ended on December 17, 2012, when the probes were intentionally sent down to the lunar surface. NASA ultimately named the impact site in honor of the late astronaut Sally K. Ride, who was America's first woman in space and a member of the GRAIL mission team.