Press2ToContinue writes "According to a NASA news release, 'Twin
lunar-orbiting NASA spacecraft that have allowed scientists to
learn more about the internal structure and composition of the
moon are being prepared for their controlled descent and impact
on a mountain near the moon's north pole at about 2:28 p.m. PST
(5:28 p.m. EST) Monday, Dec. 17. Ebb and Flow, the Gravity
Recovery and Interior Laboratory (GRAIL) mission probes, are
being sent purposely into the lunar surface because their low
orbit and low fuel levels preclude further scientific
operations. The duo's successful prime and extended science
missions generated the highest resolution gravity field map of
any celestial body. The map will provide a better understanding
of how Earth and other rocky planets in the solar system formed
and evolved. Both spacecraft will hit the surface at 3,760 mph
(1.7 kilometers per second). No imagery of the impact is
expected because the region will be in shadow at the time.'
That's too bad; observing the impacts