by Erin Blakemore

Over 400 million miles away, two groups of chunky asteroids spin around Jupiter, trapped by the planet’s orbit.

They’re known as Trojan asteroids. This month, a new probe will begin a 12-year mission to study their secrets.

The spacecraft, called Lucy, has an ambitious aim. It will be the first mission to study the Trojan asteroids, and the most complex in terms of number of destinations ever launched.

Lucy is scheduled to visit eight asteroids in the next decade. Researchers hope that the data — drawn from asteroids with different characteristics — will yield insight into the formation of the universe.

Asteroids are the leftovers of the earliest days of our solar system — big chunks of rock that don’t rate the designation “planet.” There are about 1.1 million known asteroids in the solar system.

Most asteroids orbit the sun. But Trojan asteroids share planets’ orbits. Scientists named them after characters in the Iliad, the epic poem set during the legendary Trojan War in ancient Greece.

NASA scientists want a close-up view of Jupiter’s Trojans. They’re “the fossils of planet formation,” says Hal Levison of planetary scientist at the Southwest Research Institute and the mission’s principal investigator.

Named after the fossilized, early hominid Australopithecus who became an iconic symbol of humans’ ancient ancestry, the Lucy probe is equipped with a plaque aimed at future humans who might one day find her remains orbiting the sun. It’s covered with quotations and song lyrics, many from band members of the Beatles. When anthropologists dug up Lucy’s skeleton in the 1970s — the oldest ever found at the time — they christened her after singing the band’s song “Lucy in the Sky With Diamonds.”