NASA Grail Twins Make Impact with Moon

The lunar-orbiting twins of NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission made impact on an unnamed mountain on the moon Monday, Dec. 17, 2012. The spacecraft were purposely sent into the moon because after successful prime and extended science missions, their low orbit and low fuel levels preclude further scientific operations. The mission has helped scientists learn about the moon’s internal structure and composition in unprecedented detail.