Gravity Field Mystery of the Moon Solved By NASA GRAIL Mission

Gravity Field Map of the Moon

The Gravity Recovery and Interior Laboratory (GRAIL) mission by NASA has solved one of the moon's mysteries, its ever changing gravitational field. Mass concentrations under the lunar surface changes the gravitational field in the area that can either push or pull approaching spacecraft.

The GRAIL mission has mapped the gravity field of the lunar surface (see image).

The image on the left, known as a Mercator projection (similar to Earth maps), represents the entire surface of the moon with the far side of the moon (the dark side) at the center of the map and the nearside (as seen from the Earth), on the left and right side. The red parts correspond to mass excesses which create areas of higher local gravity, and the blue parts correspond to mass deficits which create areas of lower local gravity.

NASA's GRAIL mission involves two washing machine sized satellites that are placed on the same lunar orbit. It mapped the gravity of the lunar surface as well as its interior and thermal history. It also has a set of cameras known as MoonKAM that are used for NASA's education and public outreach project.