Dozens of Greek and Armenian priests and worshippers exchanged blows at one of Christianity's holiest shrines on Orthodox Palm Sunday, and used palm fronds to pummel police who tried to break up the brawl.

The fight came amid growing rivalry over religious rights at the Church of the Holy Sepulcher, built over the site in Jerusalem where tradition says Jesus was buried and resurrected.

It erupted when Armenian clergy kicked out a Greek priest from their midst, pushed him to the ground and kicked him, according to witnesses.

When police intervened, some worshippers hit them with the palm fronds they were holding for the religious holiday. The Eastern Orthodox churches, including the Armenians and Greek Orthodox, follow a different calendar from Western Christians and celebrate Easter next Sunday.

Two Armenian worshippers who attacked the Greek Orthodox clergy were briefly detained by Israeli police. Scores of Armenian supporters then protested outside the police station during the questioning of the two, beating drums and chanting.

The Holy Sepulcher is shared by several Christian denominations according to a centuries-old arrangement known as the "status quo."

Each denomination jealously guards its share of the basilica, and fights over rights at the church have intensified in recent years, particularly between the Armenians and Greeks.

Father Pakrad, an Armenian priest, said the presence of the Greek priest during the Armenian observances violated the status quo. "Our priests entered the tomb. They kicked the Greek monk out of the Edicule," he said, referring to the tomb area.

Pakrad accused the Greek Orthodox Christians of trying to step on the Armenians' rights. "We are the weak ones, persecuted by them for many centuries."

The Greek Orthodox Patriarch in the Holy Land, Theofilos III, told The Associated Press that the Armenians are pushing to change the rules, challenging what he said was the dominance of the Greek church in the Holy Land.

"This behavior is criminal and unacceptable by all means," he said. "They wanted to trespass on the status quo concerning the order that regulates the services between the various communities."

The Church of the Nativity in nearby Bethlehem — where Jesus is said to have been born — also falls under the status quo arrangement. Last year, pre-Christmas cleaning in that church turned ugly when robed Greek Orthodox and Armenian priests went at each other with brooms and stones.

Scientists are priming two spacecraft to slam into the moon's South Pole to see if the lunar double whammy reveals hidden water ice.

The Earth-on-moon violence may raise eyebrows, but NASA's history shows that such missions can yield extremely useful scientific observations.

"I think that people are apprehensive about it because it seems violent or crude, but it's very economical," said Tony Colaprete, the principal investigator for the mission at NASA's Ames Research Center in Moffett Field, Calif.

NASA's previous Lunar Prospector mission detected large amounts of hydrogen at the moon's poles before crashing itself into a crater at the lunar South Pole. Now the much larger Lunar Crater and Observation Sensing Satellite (LCROSS) mission, set for a February 2009 moon crash, will take aim and discover whether some of that hydrogen is locked away in the form of frozen water.

LCROSS will piggyback on the Lunar Reconnaissance Orbiter (LRO) mission for an Oct. 28 launch atop an Atlas 5 rocket equipped with a Centaur upper stage. While the launch will ferry LRO to the moon in about four days, LCROSS is in for a three-month journey to reach its proper moon smashing position. Once within range, the Centaur upper stage doubles as the main 4,400 pound (2,000 kg) impactor spacecraft for LCROSS.

The smaller Shepherding Spacecraft will guide Centaur towards its target crater, before dropping back to watch - and later fly through - the plume of moon dust and debris kicked up by Centaur's impact. The shepherding vehicle is packed with a light photometer, a visible light camera and four infrared cameras to study the Centaur's lunar plume before it turns itself into a second impactor and strikes a different crater about four minutes later.

"This payload delivery represents a new way of doing business for the center and the agency in general," said Daniel Andrews, LCROSS project manager at Ames, in a statement. "LCROSS primarily is using commercial-off-the-shelf instruments on this mission to meet the mission's accelerated development schedule and cost restraints."

Figuring out the final destinations for the $79 million LCROSS mission is "like trying to drive to San Francisco and not knowing where it is on the map," Colaprete said. He and other mission scientists hope to use observations from LRO and the Japanese Kaguya (Selene) lunar orbiter to map crater locations before LCROSS dives in.

"Nobody has ever been to the poles of the moon, and there are very unique craters - similar to Mercury - where sunlight doesn't reach the bottom," Colaprete said. Earth-based radar has also helped illuminate some permanently shadowed craters. By the time LCROSS arrives, it can zero in on its 19 mile (30 km) wide targets within 328 feet (100 meters).

Scientists want the impactor spacecraft to hit smooth, flat areas away from large rocks, which would ideally allow the impact plume to rise up out of the crater shadows into sunlight. That in turn lets LRO and Earth-based telescopes see the results.

"By understanding what's in these craters, we're examining a fossil record of the early solar system and would occurred at Earth 3 billion years ago," Colaprete said. LCROSS is currently aiming at target craters Faustini and Shoemaker, which Colaprete likened to "fantastic time capsules" at 3 billion and 3.5 billion years old.

LCROSS researchers anticipate a more than a 90 percent chance that the impactors will find some form of hydrogen at the poles. The off-chance exists that the impactors will hit a newer crater that lacks water - yet scientists can learn about the distribution of hydrogen either way.

"We take [what we learn] to the next step, whether it's rovers or more impactors," Colaprete said.

This comes as the latest mission to apply brute force to science.

The Deep Impact mission made history in 2005 by sending a probe crashing into comet Tempel 1. Besides Lunar Prospector's grazing strike on the moon in 1999, the European Space Agency's Smart-1 satellite dove more recently into the lunar surface in 2006.

LCROSS will take a much more head-on approach than either Lunar Prospector or Smart-1, slamming into the moon's craters at a steep angle while traveling with greater mass at 1.6 miles per second (2.5 km/s). The overall energy of the impact will equal 100 times that of Lunar Prospector and kick up 1,102 tons of debris and dust.

"It's a cost-effective, relatively low-risk way of doing initial exploration," Colaprete said, comparing the mission's approach to mountain prospectors who used crude sticks of dynamite to blow up gully walls and sift for gold. Scientists are discussing similar missions for exploring asteroids and planets such as Mars.

Nevertheless, Colaprete said they "may want to touch the moon a bit more softly" after LCROSS has its day.

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U.S. scientists have developed a microfiber fabric that generates its own electricity, making enough current to recharge a cell phone or ensure that a small MP3 music player never runs out of power.

If made into a shirt, the fabric could harness power from its wearer simply walking around or even from a slight breeze, they reported Wednesday in the journal Nature.

"The fiber-based nanogenerator would be a simple and economical way to harvest energy from the physical movement," Zhong Lin Wang of the Georgia Institute of Technology, who led the study, said in a statement.

The nanogenerator takes advantage of the semiconductive properties of zinc oxide nanowires -- tiny wires 1,000 times smaller than the width of a human hair -- embedded into the fabric. The wires are formed into pairs of microscopic brush-like structures, shaped like a baby-bottle brush.

One of the fibers in each pair is coated with gold and serves as an electrode. As the bristles brush together through a person's body movement, the wires convert the mechanical motion into electricity.

"When a nanowire bends it has an electric effect," Wang said in a telephone interview. "What the fabric does is it translates the mechanical movement of your body into electricity."

His team made the nanogenerator by first coating fibers with a polymer, and then a layer of zinc oxide. They dunked this into a warm bath of reactive solution for 12 hours. This encouraged the wires to multiply, coating the fibers.

"They automatically grow on the surface of the fiber," Wang said. "In principal, you could use any fiber that is conductive."

They added another layer of polymer to prevent the zinc oxide from being scrubbed off. And they added an ultra-thin layer of gold to some fibers, which works as a conductor.

To ensure all that friction was not just generating static electricity, the researchers conducted several tests. The fibers produced current only when both the gold and the zinc oxide bristles brushed together.

So far, Wang said the researchers had demonstrated the principle and developed a small prototype.

"Our estimates show we can have up to 80 milliwatts per square meter of this fabric. This is enough to power a little iPod or charge a cell phone battery," he said.

"What we've done is demonstrate the principle and the fundamental mechanism."

Wang said the material could be used by hikers and soldiers in the field and also to power tiny sensors used in biomedicine or environmental monitoring.

One major hurdle remains: zinc oxide degrades when wet. Wang's team is working on a process that would coat the fibers to protect the fabric in the laundry.

(Editing by Maggie Fox and Alan Elsner)

(julie.steenhuysen@reuters.com ; +1 312 408 8131))