Lucy

Key facts

Mission & specifications

Mission

Lucy is NASA's mission to a population of asteroids no spacecraft had ever visited: the Jupiter Trojans. These are two great swarms of primitive bodies that share Jupiter's orbit around the Sun, trapped at gravitationally stable points sixty degrees ahead of and behind the giant planet. Captured there since the Solar System's earliest days, they are thought to be pristine leftovers from the era of planet formation — which is why the mission is named for the famous fossil that illuminated human origins. Launched in 2021, Lucy is on an extraordinary twelve-year, looping path that uses repeated Earth gravity assists to swing out to both Trojan swarms in turn. Over the mission it will fly past a record number of asteroids — first a small main-belt body as a rehearsal, then a series of Trojans of varying size, colour and composition — more than any single spacecraft has ever visited. On its first asteroid encounter, Lucy made a surprising discovery: the little asteroid Dinkinesh turned out to have a tiny moon of its own, which itself proved to be a contact binary — two objects touching. Now cruising outward toward its first Trojan flyby later this decade, Lucy is set to open a window on a class of worlds never seen up close — fossils of the outer Solar System.

1. 2021Launch toward the TrojansLaunch

   Lucy begins a twelve-year tour of the Jupiter Trojan asteroids.

2. 2023Asteroid DinkineshFlyby

   A rehearsal flyby finds Dinkinesh has a tiny contact-binary moon.

3. 2025Asteroid DonaldjohansonFlyby

   A second main-belt rehearsal en route to the Trojan swarms.

4. 2027First Trojan: Eurybates (planned)Arrival

   Lucy is planned to reach its first Jupiter Trojan asteroid.

Images

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