“This is way cool. That will be the end of the technical discussion,” said Pete Worden, director of the Ames Research Center, which is managing the mission. As he spoke, his image was flashed onto a giant inflatable movie screen on a mall at the NASA center.

Just before 7 p.m., the spacecraft executed a maneuver that will bring it into position for the collision.

If everything goes according to plan, a NASA satellite will steer the Centaur into the Cabeus crater at 4:30 a.m. Friday. Four minutes later, the satellite, called the Lunar Crater Observation and Sensing Sateite, or LCROSS, will fly through the dust raised by the Centaur’s crash. When it does, its nine spectroscopes and cameras will sample the debris cloud for traces of water.

Many scientists have speculated that large amounts of ice could lie hidden in permanently shadowed polar craters.

Finding water on the moon would be as important as finding gold, since it would make building a colony on the moon much easier than transporting water from Earth at $50,000 a pound.

Among those waiting out the night to witness the collision was Stephanie Vaughan, 30, who recently moved to the Bay Area from Los Angeles to begin her law career.

“This is a once in a lifetime thing,” she said, as she huddled against the chill in a folding chair. She wasn’t sure she could stay awake for the crash, but hoped the pizza and beer her friends had brought along might help.

John Thompson, 18, from Mountain View, wrapped himself in a sheet of aluminum foil to keep out the cold. He said searching for water on the moon is a good idea, “because if we find water, we could live up there.”

He said he’d be willing to volunteer: “I’m getting tired of Earth.”