Nasa's experiment last month to find water on the Moon was a major success, US scientists have announced.
The space agency smashed a rocket and a probe into a large crater at the lunar south pole, hoping to kick up ice.
Scientists who have studied the data now say instruments trained on the impact plume saw copious quantities of water-ice and water vapour.
One researcher described this as the equivalent of "a dozen two-gallon buckets" of water.
"We didn't just find a little bit; we found a significant amount," said Anthony Colaprete, chief scientist for the Lunar Crater Observation and Sensing Satellite (LCROSS) mission.
No doubt
October's experiment involved driving a 2,200kg Centaur rocket stage into the 100km-wide Cabeus Crater, a permanently shadowed depression at the Moon's far south.
At the time, scientists were hoping for a big plume of debris some 10km high which could be seen by Earth telescopes.
LCROSS (Nasa)
The following probe was designed to analyse the debris plume
The actual debris cloud was much smaller, about 1.6km high, but sufficiently large to betray the evidence researchers were seeking.
The near-infrared spectrometer on the LCROSS probe that followed the rocket into the crater detected water-ice and water vapour. The ultraviolet-visible spectrometer provided additional confirmation by identifying the hydroxyl (OH) molecule, which arises when water is broken apart in sunlight.
"We were able to match the spectra from LCROSS data only when we inserted the spectra for water," Dr Colaprete said.
"No other reasonable combination of other compounds that we tried matched the observations. The possibility of contamination from the Centaur also was ruled out."
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The total quantity of H2O spied by the instruments was more than 100kg. It came out of a 20m-30m wide hole dug up by the impacting Centaur rocket.
'Significant' water found on Moon
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