NASA discovery makes a splash

Scientists have found "significant" amounts of water in a crater at the moon's south pole, a major discovery that will dramatically revise the characterization of the moon as a dead world and probably make it a more attractive destination for future human space missions.

"The moon is alive," said Anthony Colaprete, the chief scientist for the Lunar Crater Observation and Sensing Satellite mission.

That mission, which on Oct. 9 used a rocket to punch a hole about 100 feet across in the moon's surface, then measured about 25 gallons of water in the form of vapor and ice. Although that's not enough to swim in, it could be evidence there is enough water in permanently shaded craters at the poles for future astronauts to live off the land.

"Indeed, yes, we found water. And we didn't find just a little bit. We found a significant amount," said Colaprete, holding up gallon water buckets for emphasis.

NASA plans under review by the Obama administration call for a return to the moon at the end of the next decade and construction of a lunar base in which astronauts could live and work for months at a time. The presence of large quantities of water would make wthat plan more practical, because water could be used for drinking, respiration and even to make rocket fuel.

A resource-rich moon also could serve as the perfect low-gravity launching pad for missions that would carry astronauts and their families elsewhere in the solar system.

"This is painting a surprising new picture of the moon. This is not your father's moon," said Greg Delory, a space scientist at the University of California, Berkeley. He referred to the fact that, after the Apollo missions of the 1960s and '70s, the moon was regarded as a dead, forbidding place with little to offer future explorers.

The findings indicate that the moon retains the power to surprise. "What's really exciting is we've only hit one spot," said Peter Schultz, a geology professor at Brown University and a co-investigator on the mission. "It's kind of like when you're drilling for oil. Once you find it in one place, there's a greater chance you'll find more nearby."

No cloud at first

The $79 million lunar crater mission was launched in June to try to uncover the source of large quantities of hydrogen that had been measured by other spacecraft in lunar craters at the poles. If there was water on the moon, scientists reasoned, it would be in these shadowed craters, which haven't seen sunlight in billions of years.

The satellite targeted the Cabeus crater at the south pole, first steering its companion Centaur rocket into the surface. The satellite then flew through the cloud of debris and dust kicked up by the Centaur, using its near-infrared and visible light spectrometers, along with other instruments, to taste the contents of the debris cloud. Spectrometers identify compounds by analyzing the light they emit or absorb.

No cloud showed up at first, creating worries that the Centaur had hit rock. But the scientific team became excited when it started looking at the data transmitted back to Earth just before the satellite crashed as planned a short distance from the Centaur.

The "eureka" moment came in recent weeks when the team realized a strong signature for water had been picked up by more than one instrument. "It's a pretty tight fit for water vapor and ice," Colaprete said in a briefing at Ames Research Center in Mountain View, Calif., which managed the mission.

A new question

This is not the first discovery of water on the moon. Several weeks ago, India's Chandrayan spacecraft found clear signs of a microscopic film of water mixed in with lunar soils over large areas of the moon. But those amounts were so insignificant that it is unlikely the water would be of use to colonists. This latest discovery, however, is a potentially significant source of water.

The question now is this: Where did the water come from? Possible sources include comets and asteroids, which are considered a likely source of the water on Earth. It's also possible the hydrogen was delivered by solar wind to the lunar surface, where it was converted to water. In shadowed craters, the water could be stored in the form of ice for billions of years. Polar craters on the moon are some of the coldest places in the solar system, with temperatures dipping below minus-360 degrees.