Scientists studied the full results of an experiment that smashed a rocket and a probe into a lunar crater last year.
The impacts kicked up large amounts of rock and dust, revealing a suite of fascinating chemical compounds and far more water than anyone had imagined.
A Nasa-led team tells Science magazine that about 155kg of water vapour and water-ice were blown out of the crater.
The researchers’ analysis suggests the lunar regolith, or soil, at the impact site contains 5.6% by weight of water-ice.
“That’s a significant amount of water,” said Anthony Colaprete, from the US space agency’s Ames research centre.
“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.”