Launched in 2021, what is the mission of NASA's space probe "Lucy"?

Over its 12-year mission, Lucy will explore a record-breaking number of asteroids: it will fly by three in the belt of asteroids that circle the Sun between the orbits of Mars and Jupiter, and then eight Trojans, which includes five asteroid targets and the satellites of three of those. Lucy also will fly by Earth three times to get a push from its gravity, making it the first spacecraft to return to the vicinity of Earth from the outer solar system.