The DART spacecraft soared into the night sky at 10:21 p.m. Pacific time on Tuesday from Vandenberg U.S. Space Force Base, about 150 miles northwest of Los Angeles, carried aboard a SpaceX-owned Falcon 9 rocket.
The DART payload, about the size of a vending machine, was released from the booster a few minutes after launch to begin a 10-month journey into space, some 6.8 million miles (11 million km) from Earth.
Moments later, the rocket's reusable lower stage flew back to Earth and safely touched down on a landing vessel floating in the Pacific in what has become a routine part of the cost-cutting launch sequence pioneered by SpaceX.
DART will fly under the guidance of NASA's flight directors until the last hours of its odyssey when control will be handed over to an autonomous on-board navigation system.
The mission's finale will test the spacecraft's ability to alter an asteroid's trajectory with sheer kinetic force, plowing into it at high speed to nudge the space boulder off course just enough to keep our planet out of harm's way.