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The moon no longer seems to be a dry, barren world. U.S. scientists Friday announced that they have confirmed the presence of water in a crater that lies near the lunar south pole.

“Yes, indeed, we found water and we didn't just find a little bit – we found a significant amount,” said Anthony Colaprete, the lead scientist overseeing the mission for the U.S. National Aeronautics and Space Administration.

The announcement is certainly good news for those who hope to see human colonists on the moon some day. Water would be an essential requirement for long-term habitation.

The scientists made the discovery by analyzing data from a rocket body and probe, called the Lunar Crater Observation and Sensing Satellite, that were deliberately smashed into the moon last month.

At the time of the twin impacts, the mission looked like a public-relations dud because it didn't produce a cloud of debris clearly visible from Earth. However, NASA scientists had insisted they were able to gather ample information from the LCROSS probe, which watched the first rocket body slam into the moon before it hit the surface, too.

After weeks of assessing the data, the NASA team called a news conference Friday to announce the preliminary results.

The rocket impact produced a new crater between 20 and 30 meters across, Dr. Colaprete said. The plumb of dust kicked up by the crash contained the equivalent of “a dozen, two-gallon buckets worth of water,” he added.

“It would be water you could drink – it's water like any other water.”

Dr. Colaprete acknowledged that a lot more work – and likely more lunar missions – will be needed to produce an accurate estimate of how much water is on the moon.

Even so, one thing is certain – the LCROSS mission has already helped overturn traditional thinking about Earth's pock-marked natural satellite.

“This is not your father's moon,” said Gregory Delory of the University of California at Berkeley. “Rather than a dead and unchanging world, it could in fact be a very dynamic and interesting one.”

In recent years, probes orbiting the moon have provided tantalizing clues that the moon's surface contains traces of hydrogen – a key component of water.

Some scientists have speculated that vast stores of frozen water could exist near the lunar poles, where the sun doesn't rise much above the horizon. Some crater bottoms are in perpetual darkness and the temperature dips to minus 238, potentially preserving water ice in a permanent deep freeze.

But other scientists had doubted the existence of lunar water.

“Now we know that water is there, thanks to LCROSS. We can begin in earnest to go to the next set of questions,” Dr. Delory said.

For one thing, the experts don't know the origin of the water. It might have come from comets – dirty cosmic snowballs – that have rained down on the moon over billions of years. Or, it might have been produced by solar wind, which is basically an ionized gas streaming off the sun and composed mostly of hydrogen. Reactions on the surface of the moon could have merged the hydrogen with oxygen to produced trace amounts of water.

“Other intriguing possibility is that the moon itself may be the source of the water through internal activity,” speculated Dr. Delory.

The results of the LCROSS mission come at a time when the Obama administration is reviewing the United States' long-term space plans. Some space enthusiasts hope lunar water could help reduce the cost of moon colonies as well as deep-space exploration. Water can be broken down into hydrogen and oxygen to create rocket fuel.

But other experts caution that it would likely be extremely pricey to separate the water from lunar soil. Although the moon might contain “significant amounts” of water, it is still drier than most deserts on Earth, Dr. Colaprete acknowledged.