... GRAIL mission solves mystery of Moonт??s surface gravity . ... NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission has uncovered the origin of massive invisible regions that make the Moon's gravity uneven, a phenomenon that affects the operations of lunar-orbiting spacecraft. ... GRAIL scientists found the mascons by combining the gravity data from GRAIL with sophisticated computer models of large asteroid impacts and known detail about the geologic evolution of the impact craters. ...