LOS ANGELES - The moon has come a long way since Galileo first peered at it through a telescope. Unmanned probes have circled around it and landed on its surface. Twelve American astronauts have walked on it. And lunar rocks and soil have been hauled back from it.

Despite being well studied, Earth's closest neighbor remains an enigma.

Over the New Year's weekend, a pair of spacecraft the size of washing machines are set to enter orbit around it in the latest lunar mission. Their job is to measure the uneven gravity field and determine what lies beneath - straight down to the core.

Since rocketing from the Florida coast in September, the near-identical Grail spacecraft have been independently traveling to their destination and will arrive 24 hours apart. Their paths are right on target that engineers recently decided not to tweak their positions.

"Both spacecraft have performed essentially flawlessly since launch, but one can never take anything for granted in this business," said mission chief scientist Maria Zuber of the Massachusetts Institute of Technology.

The nail-biting part is yet to come. On New Year's Eve, one of the Grail probes - short for Gravity Recovery and Interior Laboratory - will fire its engine to slow down so it could be captured into orbit.

This move will be repeated by the other the following day.

Engineers said the chances of the probes overshooting are slim since their trajectories have been precise. Getting struck by a cosmic ray may prevent the completion of the engine burn and they won't get boosted into the right orbit.

"I know I'm going to be nervous. I'm definitely a worrywart," said project manager David Lehman of NASA's Jet Propulsion Laboratory, which manages the $496 million, three-month mission.

Once in orbit, the spacecraft will spend the next two months flying in formation and chasing one another around the moon until they are about 35 miles above the surface with an average separation of 124 miles. Data collection won't begin until March.

Previous missions have attempted to measure lunar gravity with mixed success. Grail is the first mission dedicated to this goal.

As the probes circle the moon, regional changes in the lunar gravity field will cause them to speed up or slow down. This in turn will change the distance between them. Radio signals transmitted by the spacecraft will measure the slight distance gaps, allowing researchers to map the underlying gravity field.

Using the gravity information, scientists can deduce what's below or at the lunar surface such as mountains and craters and may help explain why the far side of the moon is more rugged than the side that faces Earth.

The probes are officially known as Grail-A and Grail-B. Several months ago, NASA hosted a contest inviting schools and students to submit new names. The probes will be christened with the winning names after the second orbit insertion, Zuber said.

Besides the one instrument on board, each spacecraft also carries a camera for educational purposes. Run by a company founded by Sally Ride, the first American woman in space, middle school students from participating schools can choose their own lunar targets to image during the mission.

A trip to the moon is typically relatively quick. It took Apollo astronauts three days to get there. Since Grail was launched from a relatively small rocket to save on costs, the journey took 3 1/2 months.

Scientists expect the mission to yield a bounty of new information about the moon, but don't count on the U.S. sending astronauts back anytime soon. The Constellation program was canceled last year by President Barack Obama, who favors landing on an asteroid as a stepping stone to Mars.

Philippine floods death toll jumps to nearly 1,500

More than 60,000 homeless in flooded villages

MANILA, Philippines (AP) - The death toll from flash floods that swept away entire villages in the southern Philippines climbed to nearly 1,500 early Tuesday, as authorities widened their search for bodies.

The Office of Civil Defense's latest tally listed 891 dead in Cagayan de Oro and an additional 451 in nearby Iligan city. The rest came from several other provinces. Most of the dead are unidentified.

"The search will continue as long as we are recovering bodies," said Civil Defense head Benito Ramos.

He said that decomposing remains were retrieved floating in the sea as far as 60 miles from the two cities where a Dec. 16 tropical storm unleashed more than a month's worth of rainfall in 12 hours, sending walls of water gushing into homes.

One of the dead was a headless girl who appeared to have been hit by logs that were carried by flash floods, Ramos said. She was among 13 bodies retrieved by a team of navy sailors.

Navy and coast guard divers were initially sent to find more bodies believed to be pinned down by logs scattered in the sea and along riverbanks, but Ramos said the operation had to be called off because waters were too murky. "It's useless to dive when you can see nothing," he said.

It was not clear how many more are missing.

More than 60,000 homeless from hundreds of flood-ravaged villages spent a miserable Christmas in jam-packed schools and gymnasiums, while the United Nations launched an urgent appeal for $28 million to help the displaced - more than half the population of Cagayan de Oro and Iligan, which are in the southern Philippines' Mindanao region.

More rains Tuesday prompted evacuations of nearly 2,000 people on the opposite side of Mindanao Island, where a child was reported missing in floods in Surigao city, the civil defense reported.

President Benigno Aquino III, who banned logging in February following previous flooding deaths that experts say were caused partly by deforestation and soil erosion, has ordered an investigation.

Communist guerrillas in the south, meanwhile, threatened to punish multinational companies they blame for environmental destruction.

Rebel spokesman Jorge Madlos told The Associated Press by telephone that they sought funds for victims from huge pineapple and banana plantations and other companies.

"Some were lukewarm to our call," Madlos said. "That'll be a factor when we decide which ones to punish first for this destruction."

Another factor in the staggering death toll was illegal settlements along Cagayan rivers. Thousands of people lived in shanties on the banks and islands directly along the water's path.