GRAIL, which is short for Gravity Recovery and Interior Laboratory, is a mission to the Moon provided by the U.S. space agency NASA. It lifted off toward the Moon on September 10, 2011, from the Space Launch Complex 17B at the Cape Canaveral Air Force Station in Florida.
Scientists heading the mission are praising the results of the mission, saying that the information being returned from the Moon will help to better explain the evolution of the rocky planets of our solar system, including our home planet Earth.
The US$496 million mission consists of two washing-machine sized probes that orbit about the Moon in tandem, analyzing its surface, structure, and composition.
When launched, the two probes were re-named Ebb and Flow, which had been suggested by fourth-grade students at Emily Dickinson Elementary School in Bozeman, Montana, as mentioned in the iTWire article "Students re-name GRAIL A and B Moon probes".
The probes are in the same orbit about the Moon, with one in the lead and the other one following. Ebb was previously called GRAIL-A and Flow was previously named GRAIL-B.
One bit of information that the GRAIL mission has discovered is that the Moon is as much as 12 miles thinner with respect to its lunar crust than previously thought. The crust is between 21 miles (34 kilometers) and 27 miles (44 kilometers) in thickness.
Page two concludes with an explanation of the YouTube video shown at the top of this first page.