Quest for lunar water starts with a bang Friday

John Johnson Jr. / Los Angeles Times

In the predawn hours Friday, a spacecraft is scheduled to punch a 13-foot-deep hole in the moon's south pole to a crater that hasn't seen sunlight in billions of years. The purpose: to find out whether ice is hidden there.

NASA's Lunar Crater Observation and Sensing Satellite, which set out for the moon in June, made a late course correction Tuesday to position itself to steer a rocket into the 2-mile-deep crater Cabeus at 7:30 a.m., EDT, Friday morning.

Four minutes later, if all goes according to plan, the spacecraft will fly through the cloud of debris that will rise above the lunar surface and linger there for less than a minute. As it passes through the cloud, the satellite's nine instruments will analyze the dust and debris for evidence of water, before crashing itself.

Scientists preparing for the collision could hardly contain their excitement over what might turn up.

"The spacecraft is looking great. I don't think we could miss the moon now if we tried," said Steve Hixson, vice president of Advanced Concepts at Northrop Grumman Aerospace Systems in Redondo Beach, Calif., which built the craft.

"It's our job to confirm there is water there," said Dan Andrews, the project manager at Ames Research Center in Mountain View, Calif., which designed the spacecraft's instruments. "But even if it's very dry, that's a good answer to have."

The LCROSS satellite was originally a $79 million add-on to the larger, $500 million Lunar Reconnaissance Orbiter, whose mission is to map the moon. But the theatrical nature of the impact event has caught the attention of the public.

Thousands of people are expected to show up Thursday night at the Ames complex south of San Francisco for an evening of music and movies that will culminate with a live video feed of the impact.

"It's kind of hard to keep on top of how much interest there is out there," Andrews said. "I've heard 10,000 are coming."

For decades after the Apollo missions of the late '60s and early '70s, scientists considered the moon to be little more than a dry wasteland.

But in 1999, NASA's Lunar Prospector mission found evidence of hydrogen, a possible indicator of water, in permanently shadowed craters at both poles. Since then, several other spacecraft have detected the same thing, leading scientists to wonder if there could be large stores of ice hidden in craters.

According to scientists, water on the moon would be as valuable as gold. Not only would it be useful to drink, should President Barack Obama continue President George W. Bush's ambitious plan to build a lunar base there after 2020, but it could be broken down to make breathable air and even rocket fuel.

Transporting water to the moon, on the other hand, costs $50,000 a pound.

The crater-observing satellite launched June 18 attached to a second spacecraft, the Lunar Reconnaissance Orbiter. Shortly after launch, the two spacecraft separated.

The orbiter continued a year-long mission to map the moon in search of landing sites for future lunar colonists. The sensing satellite went into a long, looping orbit around the Earth to line itself up for Friday's impact.

Originally, spacecraft controllers had chosen a nearby crater, Cabeus A, as the target. But last week, they decided it wasn't as good a potential source for water as Cabeus, a 60-mile-wide valley near the moon's south pole.

Andrews said satellite controllers are aiming for a spot in the northwest region of the crater, where temperatures of minus 397 degrees Fahrenheit would ensure that any water would be frozen as hard as rock.

The rocket that will hit the crater is the upper stage of the Atlas V rocket that launched both spacecraft in June. Having used its fuel, it is now a 5,200-pound projectile. About 10 hours before Friday's impact, the rocket will separate from the satellite and begin heading directly for the crater. Meanwhile, the satellite will maneuver itself into position to fly through the debris kicked up when the rocket crashes.

According to NASA, the rocket will be traveling at about 5,600-miles-an-hour when it plunges into Cabeus. That will create a dust cloud rising as much as six miles above the lunar surface, providing a rare show for amateur astronomers.

The collision can theoretically be seen throughout the southwest and as far away as Hawaii, providing the observer has a large enough telescope at hand and good viewing conditions.

Because the debris cloud from the impact is expected to last less than a minute before settling back down on the lunar surface, viewers need to be punctual and have sharp eyes.

Scientists believe the lunar water, if it's there, arrived the same way it did on Earth: through billions of years of bombardment by water-rich comets and meteors. Any water that was deposited in sunlit places would quickly be lost to space and to the moon's scorching daytime heat, which can reach 250 degrees Fahrenheit. But in shadowed craters, the water could remain as ice for eons.

Bernard Foing, the project scientist for the European Smart-1 spacecraft that took pictures of the crater several years ago, said the floor of Cabeus contains a number of small craters that appear old enough to have trapped water from comets and water-rich asteroids.

Andrews said it could be days or weeks after the impact before scientists conclude that there is, or is not, water at the pole. Besides the crater-observing spacecraft, observatories around the world will be watching, as will with the Hubble Space Telescope and the Lunar Reconnaissance Orbiter.