NASA set to crash on the moon -- twice

(CNN) -- Two U.S. spacecraft are set to crash on the moon Friday. On purpose. And we're all invited to watch.

An artist's rendering shows the LCROSS spacecraft, left, separating from its Centaur rocket.

NASA's Lunar Crater Observation and Sensing Satellite is scheduled to drop its Centaur upper-stage rocket on the lunar surface at 7:31 a.m. ET.

NASA hopes the impact will kick up enough dust to help the LCROSS probe find the presence of water in the moon's soil. Four minutes later, the LCROSS will follow through the debris plume, collecting and relaying data back to Earth before crashing into the Cabeus crater near the moon's south pole.

The LCROSS is carrying spectrometers, near-infrared cameras, a visible camera and a visible radiometer. These instruments will help NASA scientists analyze the plume of dust -- more than 250 metric tons' worth -- for water vapor.

The orbiting Hubble Space Telescope and NASA's Lunar Reconnaissance Orbiter will watch, and photograph, the collisions. And hundreds of telescopes on Earth also will be focused on the two plumes.

NASA is encouraging amateur astronomers to join the watch party.

"We expect the debris plumes to be visible through midsized backyard telescopes -- 10 inches and larger," said Brian Day at NASA's Ames Research Center at Moffett Field, California. Day is an amateur astronomer who is leading education and public outreach for the LCROSS mission.

"The initial explosions will probably be hidden behind crater walls, but the plumes will rise high enough above the crater's rim to be seen from Earth," he said. The Cabeus crater lies in permanent shadow, making observations inside the crater difficult.

The impacts will not be visible to the naked eye or through binoculars. If you don't have a telescope, or you live in areas where daylight will obscure the viewing, NASA TV will broadcast the crashes live. Coverage begins at 6:15 a.m. ET Friday.

The two main components of the LCROSS mission are the shepherding spacecraft and the Centaur upper stage rocket. The spacecraft will guide the rocket to its crash site.

Data from previous space missions have revealed trace amounts of water in lunar soil. The LCROSS mission seeks a definitive answer to the question of how much water is present. NASA has said it believes water on the moon could be a valuable resource in the agency's quest to explore the solar system.

LCROSS launched with the Lunar Reconnaissance Orbiter aboard an Atlas V rocket from Cape Canaveral, Florida, on June 18.