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Wikipedia dicit:

Lucy is a planned NASA space probe that will complete 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 hominid 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 is planned to launch in 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. In 2025, it will fly by the inner main-belt asteroid 52246 Donaldjohanson, which was named after the discoverer of the Lucy hominid fossil. In 2027, it will arrive at the L4 Trojan cloud (the Greek camp of asteroids that orbits about 60° ahead of Jupiter), where it will fly by four Trojans, 3548 Eurybates (with its satellite), 15094 Polymele, 11351 Leucus, and 21900 Orus. After these flybys, Lucy will return to Earth in 2031 whereupon it will receive another slight gravity assist to take it to the L5 Trojan cloud (the Trojan camp which trails about 60° behind Jupiter), where it will visit the binary Trojan 617 Patroclus with its satellite Menoetius in 2033. The mission may end with the Patroclus–Menoetius flyby, but at that point Lucy will be in a stable, 6-year orbit between the L4 and L5 clouds, and a mission extension will be possible.

Three instruments comprise the payload: a high-resolution visible imager, an optical and near-infrared imaging spectrometer and a thermal infrared spectrometer.

Exploration of Jupiter Trojans is one of the high priority goals outlined in the Planetary Science Decadal Survey. Jupiter Trojans have been observed by ground-based telescopes and the Wide-field Infrared Survey Explorer to be “dark with… surfaces that reflect little sunlight”. Jupiter is 5.2 AU (780×106 km; 480×106 mi) from the Sun, or about five times the Earth-Sun distance. The Jupiter Trojans are at a similar distance but can be somewhat farther or closer to the Sun depending on where they are in their orbits. There may be as many Trojans as there are asteroids in the asteroid belt.

Video credit: NASA Goddard