NASA has successfully crashed two spacecraft into the moon's south pole in a hunt for hidden ice, the space agency said Friday.

A 2.2-ton Centaur, the upper stage of the Atlas V rocket that carried the Lunar Crater Observation and Sensing Satellite, or LCROSS for short, into space struck the moon first at 7:31 a.m. EDT (1131 GMT).

Four minutes later, the LCROSS hit the Cabeus crater floor near the moon's south pole.

NASA had expected the strikes to kick up a plume of lunar dirt to an altitude of about 6.2 miles (10 kilometers) and produce a flash lasting about 30 seconds. However, grainy thermal images carried on NASA's television station showed no apparent flashes as the rocket struck.

The LCROSS carried five cameras and four other scientific instruments and NASA had touted live photos on its web site. But those images didn't occur. NASA officials say they are sure the two spacecraft struck the moon and are trying to determine what happened to the pictures.

"It's hard to tell what we saw," said Michael Bicay, director of science at NASA's Ames Research Center in Moffett Field, California. "We have some confirmation form the (control room) that we had a thermal signature."

NASA said on its web site after the strikes that the LCROSS science team is making a preliminary assessment of approximately four minutes of data collected from the spacecraft.

"We don't anticipate anything about presence or absence of water immediately. It's going to take us some time," said Anthony Colaprete, project scientist and principal investigator for the LCROSS mission.

Astronomers at the Palomar Observatory outside of San Diego said an hour after the strikes that they saw no evidence of an impact plume through the 200-inch Hale Telescope.

The Apache Point Observatory in New Mexico focused three telescopes on the moon during the strikes but the instruments didn't detect any visual sign of a lunar debris plume.

"We didn't see anything in a quick glance at the images, but it's going to take a while to know for sure if we saw anything," said Nancy Chanover, an assistant astronomy professor at New Mexico State University.

The first and much larger strike was supposed to hit the crater with the force of 1.5 tons of TNT while the second was to be about one-third as strong.

The idea is to confirm the theory that water is hidden below the barren moonscape.

(Xinhua News Agency October 9, 2009)