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NASA has launched a spacecraft named Lucy on the first ever mission to explore eight asteroids clustered around Jupiter, in an effort to learn more about the formation of the solar system.
An Atlas V rocket blasted off before dawn on Saturday, sending Lucy on a roundabout orbital journey that is expected to last 12 years and span nearly 4 billion miles.
"I'm just elated," NASA's associate administrator, Robert Cabana, said following liftoff. "This is the coolest darn mission."
Lead scientist Hal Levison said it was like witnessing the birth of a child.
Lucy is named after the 3.2 million-year-old skeletal remains of a human ancestor found in Ethiopia nearly a half-century ago.
That discovery got its name from the 1967 Beatles song "Lucy in the Sky with Diamonds," prompting NASA to send the spacecraft soaring with band members' lyrics and other luminaries' words of wisdom imprinted on a plaque.
The unmanned vehicle is also carrying a disc made of lab-grown diamonds for one of its science instruments.
In a prerecorded video for NASA, Beatles drummer Ringo Starr paid tribute to his late colleague John Lennon, credited for writing the song that inspired the name.
"I'm so excited - Lucy is going back in the sky with diamonds. Johnny will love that," Starr said. "Anyway, if you meet anyone up there, Lucy, give them peace and love from me."
Lucy will visit eight different asteroids, known as Trojans.
Formed around 4.5 billion years ago, the Trojans are believed to be leftovers from the formation of the solar system.
"Are there mountains? Valleys? Pits? Mesas? Who knows? I'm sure we're going to be surprised," said Johns Hopkins University's Hal Weaver, who is in charge of Lucy's black-and-white camera.
"But we can hardly wait to see what images will reveal about these fossils from the formation of the solar system."
Drawing power from two huge circular solar wings, Lucy will chase down five asteroids in the leading pack of Trojans in the late 2020s.
The spacecraft will then swoop back toward Earth for another gravity assist in 2030 that will swing it back out to the trailing Trojan cluster, where it will zip past the final two targets in 2033.
Lucy will pass within 600 miles (965 kilometers) of each target, the biggest one being about 70 miles (113 kilometers) across.
Fitted with a powerful camera – known as a long-range reconnaissance imager – the probe will be able to capture high-resolution pictures of the asteroids.
It is also fitted with instruments to map the surface geology of each asteroid.
The voyage will cost an estimated $981 million (£714 million).