The crater was specifically targeted for the fact that it is located near the equator and would most likely provide rocks that have the characteristics of those originating from deep below the surface of the Moon, having been subjected to magmatic forces. In the words of Rachel Klima, a planetary geologist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md: “This rock, which normally resides deep beneath the surface, was excavated from the lunar depths by the impact that formed the Bullialdus crater. Compared to its surroundings, we found that the central portion of this crater contains a significant amount of hydroxyl — a molecule consisting of one oxygen atom and one hydrogen atom — which is evidence that the rocks in this crater contain water that originated beneath the lunar surface.”
This new evidence means that scientists can start sifting through data which has been taken from orbit and begin to re-evaluate samples taken from the original Apollo sites. These samples contained water but since the Moon was believed to be dry, it was assumed that the samples had been contaminated with water while on Earth.
As Klima so eloquently continues, “Now that we have detected water that is likely from the interior of the Moon, we can start to compare this water with other characteristics of the lunar surface. This internal magmatic water also provides clues about the Moon’s volcanic processes and internal composition, which helps us address questions about how the Moon formed, and how magmatic processes changed as it cooled.”