Category: Science / December 18, 2012 9:36 AM EST
NASA's Gravity Recovery And Interior Laboratory (GRAIL) mission came to an end on Monday (December 18) as planned when the flight operations team commanded the two spacecraft to de-orbit and impact the surface of the moon.
The first of the orbiters, Ebb, impacted a predetermined mountain near the lunar North Pole at 3:28 p.m. MT, with its twin, Flow, hitting nearby 30 seconds later. Both were traveling at 3,760 mph (1.7 kilometers per second).
Lockheed Martin built the twin robotic spacecraft and conducted flight operations for NASA's JPL since their launch on Sept. 10, 2011.
Following a successful primary and secondary science mission of mapping the gravity of the moon, the washing machine-sized spacecraft were nearly out of fuel. JPL and Lockheed Martin worked together to send both spacecraft to the surface in a controlled manner at a known location.
Grail principal investigator Dr. Maria Zuber commented on what could be discovered:
"Ebb and Flow have removed a veil from the moon and removing this veil will enable discoveries about the way the moon formed and evolved for many years to come,"
The GRAIL primary mission yielded the highest-resolution gravity field map of any celestial body. Future gravity field models developed from data collected during the extended mission will be of even higher resolution. The map will provide a better understanding of how the moon, Earth and other terrestrial planets in the solar system formed and evolved.