The pair was targeted at the Moon's southern pole - at Cabeus Crater, a depression so deep and dark that the likelihood of disturbing ice were thought to be very good.
The rocket stage went in first, followed a few minutes later by the LCROSS probe which gathered imagery and other data just before it too hit into the surface.
Another spacecraft, NASA's Lunar Reconnaissance Orbiter (LRO), was passing close by. It also was able to study the trail of material ejected into sunlight more than 15km above the circumference of Cabeus.
Scientists studied the full results of this experiment and found that the impacts kicked up large amounts of rock and dust, revealing a collection of fascinating chemical compounds and far more water than anyone had expected.
A NASA-led team tells Science magazine that about 155kg of water vapor and water-ice were blown out of the crater.
The researchers' analysis suggests the lunar soil at the impact site contains 5.6% by weight of water-ice.
Anthony Colaprete, from the US space agency's Ames research center said:
"That's a significant amount of water, and it's in the form of water-ice grains. That's good news because water-ice is very much a friendly resource to work with. You don't have to warm it very much; you just have to bring it up to room temperature to pull it out of the dirt real easy."
And he added:
"If you took just the 10km region around the impact site and say it had 5% water - that would be equivalent to about a billion gallons of water. I'm not saying that's what's there, but it just shows you that even at these small concentrations there's potential for lots of water."