Watch live: Rocket, spacecraft set to crash on moon

A four-story rocket stage with the mass of a large SUV is on track to slam into a crater on the moon's south pole Friday morning, followed quickly by a NASA spacecraft.

Watch live coverage of the impacts here starting at 6 a.m., including NASA TV's broadcast starting at 6:15 a.m.

The two collisions are planned at 7:31 a.m. and 7:35 a.m. EDT.

NASA's $79-million Lunar Crater Observation and Sensing Satellite mission, or LCROSS, hopes to confirm the presence of water ice in freezing lunar craters that haven't seen sunlight for more than a billion years.

To do so, the upper stage of an Atlas V rocket - called a Centaur - will serve as an "impactor." It will smash into the Cabeus crater at a sharp angle and at twice the speed of a bullet to kick up a curtain of debris roughly six miles high.

The Volkswagen Beetle-sized LCROSS spacecraft will dive through the plume, taking measurements with science instruments and streaming live video from its cameras.

It will crash four minutes after the Centaur.

The mission, which launched June 18 from Cape Canaveral, cleared a critical hurdle Thursday night when the satellite and Centaur separated successfully at 9:50 p.m., allowing the moon's gravity to begin pulling the rocket motor toward the surface.

Less than an hour later, the spacecraft executed a braking burn to create the four-minute, 373-mile space between them.

Check out this story for more background on the mission, as well as these NASA documents:

++ Mission fact sheet.
++ Mission press kit (coupled with information on the Lunar Reconnaissance Orbiter, which launched with LCROSS).

Click here to access the mission's Citizen Science site, where amateur astronomers are being encouraged to submit images they collect. (It's expected to be too light out in Florida to see the impacts through telescopes.)

Click here to read the flight director's blog.

And follow the mission's Twitter updates here.

IMAGES: Top, an image of the lunar south pole showing the target Cabeus crater. Credit: NMSU/MSFC Tortugas Observatory. Bottom, a map of the lunar south pole, close-up view. The LCROSS target crater, Cabeus, is shown. Credit: NASA.