Gallery: NASA ready to shoot the moon

This half of the Earth will be faced toward the moon at about 4:30 a.m. PDT when LCROSS plunges into the lunar surface. NASA is planning a series of parties at observatories and museums across the U.S. to observe the event with experts.

Excellent lighting conditions are expected in the Mountain, Pacific, Alaska and Hawaii time zones. In the Central time zone, the best viewing will be west of the Mississippi, and daybreak in the Eastern time zone will prevent viewing the plume.

Since the Sun rises no more than 1.6 degrees above the horizon at the moon's poles, shallow craters can have permanently shadowed floors where water ice can exist.

The plan.

As it approaches the moon, LCROSS will release the Centaur then brake and turn 180 degrees to allow the instrument payload to capture the Centaur impact. It will have four minutes after the Centaur crashes to collect data and transmit it back to earth before it is vaporized.

How it should work. This test, taken with a high-speed camera, shows a plume of water vapor emerging after a verticle impact into dry ice.

Credit: P. H. Schultz, Brown University and AVGR.

A similar crater could be left on the moon's surface.

Credit: NASA

LCROSS and the Centaur were launched on June 18,2009.

The flight plan.

LCROSS views the Earth on August 17, 2009 from a distance of more than 300,000 miles.

LCROSS (the streak in the center) as photographed from Earth.

Labeled composite image of the South Pole taken by New Mexico State University/ Marshall Space Flight Center, using the Tortugas 24-inch telescope.

?Credit: NMSU/MSFC

The impact site.

A closer look at the impact site.

Even closer.

This image shows the candidate craters for the crashing site - a crater called Cabeus (cricled) was selected.

The The dark blue and purple areas of the moon's north (left) and south pole show evidence of hydrogen-rich deposits covered by dessicated regolith where ice or hydrated minerals could exist.

Credit: NASA

LCROSS

The original landing site was a crater called Cabeusa A, however, last week NASA switched to crater Cabeusa (proper) after it was determined that it contained a small valley that would allow sunlight to better illuminated the crash.

A look at the LCROSS probe and the instruments that will analyze the crash of the Centaur probe. The instruments include two near-infrared spectrometers, a visible light spectrometer, two mid-infrared cameras, two near-infrared cameras, a visible camera, and a visible radiometer.

A chart of the instruments.

Range gun

The range gun for testing.

The NASA Ames Vertical Gun Range (AVGR) at NASA Ames Research Center, Moffett Field, CA.

Credit: P. H. Schultz, Brown University and AVGR

At the lab, LCROSS is being prepared for shipping.

Cleaning LCROSS.

The first stage of LCROSS's journey is aboard a FedEx truck.

The Lunar Reconnaissance Orbiter (LRO) recently began taking high-resolution images of the lunar surface.

Eagle

The LRO last week took this photograph of American space junk left on the moon, the landing site of Eagle from Apollo 11.

The Atlas Centaur at the launch site.