NASA launches Lucy probe on 12-year flight to visit eight remote asteroids

NASA's billion-dollar Lucy probe rocketed into space with a pre-dawn launch on Saturday, kicking off a 12-year, 4-billion-mile quest to make close flybys of eight unusual asteroids that represent the preserved building blocks of the solar system.

Known as Trojans, the asteroids circle the sun well beyond the main belt of rocky debris between Mars and Jupiter. They're clustered in two gravitationally bound "swarms" in the same orbit as the giant planet, one group 60 degrees ahead and the other 60 degrees behind.

NASA's Lucy probe, named after the 3.2-million-year-old bones of a celebrated early human ancestor, was launched on a trajectory setting up three velocity-boosting Earth flybys to send it first past an asteroid in the main belt between Mars and Jupiter and then on to five asteroids in one Trojan swarm and two in the other.