Suddenly, the moon looks exciting again. It has lots of water, scientists said Friday — a thrilling discovery that sent a ripple of hope for a future astronaut outpost in a place that has always seemed barren and inhospitable.
"The moon is alive," declared Anthony Colaprete, the chief scientist for the Lunar Crater Observation and Sensing Satellite mission.
Experts have long suspected there was water on the moon. Confirmation came from data churned up by two NASA spacecraft that intentionally slammed into a lunar crater last month. "Indeed, yes, we found water. And we didn't find just a little bit. We found a significant amount," Colaprete said, holding up a white gallon water bucket for emphasis.
The crash kicked up at least 25 gallons and that's only what scientists could see from the plumes of the impact, Colaprete said.
Although that's not enough to fill a bathtub, it could be evidence there is enough water at the poles for future astronauts to use to live off the land. And it's far more than anyone expected after the Apollo missions of the 1960s and '70s, which pronounced the moon a dead, forbidding world.
"This is painting a surprising new picture of the moon," said Greg Delory, a space scientist at the University of California at Berkeley. "This is not your father's moon."
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.
Because those craters were hidden from view, scientists decided the best way to find out what was in them was to go there. Early on the morning of Oct. 9, the lunar crater satellite targeted the Cabeus crater at the South Pole, first steering its companion Centaur rocket into the crater. 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 test the contents of the debris cloud.
No cloud showed up at first, causing some scientists to worry that the Centaur had hit rock. But the scientific team became excited when they started looking at the data transmitted back to Earth just before the satellite itself crashed a short distance from the Centaur.
The eureka moment came in recent weeks when the team realized a strong signature for water was picked up in more than one instrument.
"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.
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, or regolith, over large areas of the moon. But those amounts were so insignificant that it is unlikely that that water would be of use to future colonists. This latest discovery, however, is a potentially significant source of water.
It's unlikely the water, at least at this one site, is in the form of an ice sheet, Colaprete said. It's likely to be mixed in with the soil.
President George W. Bush had proposed a more than $100 billion plan to return astronauts to the moon, then go on to Mars; a test flight of an early version of a new rocket was a success last month. President Barack Obama appointed a special panel to look at the entire moon exploration program; members said NASA should focus on other missions. The decision is now up to the White House.
These new discoveries could be game-changing, because they raise the prospect that a colony on the moon could be virtually self-sustaining.
Water is not only useful for drinking, but it could be broken down into oxygen for breathing. Hydrogen and oxygen are also potent sources of rocket fuel, raising the prospect that the moon could serve as a low gravity launching pad for missions further out into the solar system.