Lucy is a NASA space probe on a 12-year journey to eight different asteroids, visiting a main belt asteroid as well as seven Jupiter trojans,  asteroids which share Jupiter's orbit around the Sun, orbiting either ahead of or behind the planet. All target encounters will be fly-by encounters. The Lucy spacecraft is the centerpiece of a US$981 million mission.

On 4 January 2017, Lucy was chosen, along with the Psyche mission, as NASA's Discovery Program missions 13 and 14 respectively.

The mission is named after the Lucy hominin skeleton because the study of Trojans could reveal the "fossils of planet formation": materials that clumped together in the early history of the Solar System to form planets and other bodies. The Australopithecus itself was named after the 1967 Beatles song "Lucy in the Sky with Diamonds", Lucy itself is also carrying a disc made of lab-grown diamonds for her L'TES instrument.

Lucy was launched from Cape Canaveral SLC-41 on 16 October 2021 on the 401 variant of a United Launch Alliance Atlas V launch vehicle, after which it will gain two gravity assists from Earth; one in 2022, and one in 2024.

Approximately  4 1/4" by 3 1/4"