NASA’s Lucy Mission Gears Up to Meet a 150-Million-Year-Old Space Relic

Donaldjohanson, a main belt asteroid, could be a relic of a cosmic collision that took place 150 million years ago. Scientists believe its unique shape and slow spin may have been shaped by thermal forces over time.

As NASA’s Lucy spacecraft prepares for a flyby in 2025, researchers hope to uncover new clues about its origins and connections to other asteroids. Named after the paleontologist who found the famous Lucy fossil, this asteroid visit is part of a grander mission to explore Jupiter’s Trojan asteroids and decode the history of our solar system.

A Peculiar Space Rock with a Mysterious Past

Scientists at the Southwest Research Institute (SwRI) have developed new models suggesting that the main belt asteroid (52246) Donaldjohanson likely formed around 150 million years ago when a larger asteroid broke apart. Since then, its orbit and rotation have undergone significant changes. On April 20, 2025, NASA’s Lucy spacecraft will fly past this three-mile-wide asteroid, collecting data that could offer new insights into its formation and evolution by analyzing its shape, surface geology, and cratering history.

“Based on ground-based observations, Donaldjohanson appears to be a peculiar object,” said SwRI’s Dr. Simone Marchi, deputy principal investigator of the SwRI-led Lucy mission and lead author of research published in The Planetary Science Journal. “Understanding the formation of Donaldjohanson could help explain its peculiarities.”

“Data indicates that it could be quite elongated and a slow rotator, possibly due to thermal torques that have slowed its spin over time,” added David Vokrouhlický, a professor at the Charles University, Prague, and co-author of the research.

A Family Connection to Erigone Asteroids

Lucy’s target is a common type of asteroid, composed of silicate rocks and perhaps containing clays and organic matter. The new paper indicates that Donaldjohanson is likely a member of the Erigone collisional asteroid family, a group of asteroids on similar orbits that was created when a larger parent asteroid broke apart. The family originated in the inner main belt not very far from the source regions of near-Earth asteroids (101955) Bennu and (162173) Ryugu, recently visited respectively by NASA’s OSIRIS-REx and JAXA’s Hayabusa2 missions.

Awaiting the Flyby for Surprises

“We can hardly wait for the flyby because, as of now, Donaldjohanson’s characteristics appear very distinct from Bennu and Ryugu. Yet, we may uncover unexpected connections,” Marchi said.

“It’s exciting to put together what we’ve been able to glean about this asteroid,” said Keith Noll, Lucy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But Earth-based observing and theoretical models can only take us so far – to validate these models and get to the next level of detail we need close-up data. Lucy’s upcoming flyby will give us that.”

Donaldjohanson is named for the paleontologist who discovered Lucy, the fossilized skeleton of an early hominin found in Ethiopia in 1974, which is how the Lucy mission got its name. Just as the Lucy fossil provided unique insights into the origin of humanity, the Lucy mission promises to revolutionize our knowledge of the origin of humanity’s home world. Donaldjohanson is the only named asteroid yet to be visited while its namesake is still living.

Lucy’s Ambitious Mission to the Trojans

“Lucy is an ambitious NASA mission, with plans to visit 11 asteroids in its 12-year mission to tour the Trojan asteroids that are located in two swarms leading and trailing Jupiter,” said SwRI’s Dr. Hal Levison, who is the principal investigator of the mission. “Encounters with main belt asteroids not only provide a close-up view of those bodies but also allow us to perform engineering tests of the spacecraft’s innovative navigation system before the main event to study the Trojans. These relics are effectively fossils of the planet formation process, holding vital clues to deciphering the history of our solar system.”

Reference: “A Pre-flyby View on the Origin of Asteroid Donaldjohanson, a Target of the NASA Lucy Mission” by Simone Marchi, David Vokrouhlický, David Nesvorný, William F. Bottke, Josef Ďurech and Harold F. Levison, 17 March 2025, The Planetary Science Journal.
DOI: 10.3847/PSJ/adb4f4

Lucy is NASA’s pioneering mission designed to explore Jupiter’s Trojan asteroids, a group of space rocks that share the planet’s orbit and are thought to be remnants of the early solar system. As the 13th mission in NASA’s Discovery Program, Lucy aims to provide insights into planetary formation by studying these ancient celestial bodies.

The mission is led by principal investigator Dr. Hal Levison from the Southwest Research Institute’s Boulder, Colorado, branch, with the institute’s headquarters in San Antonio. NASA’s Goddard Space Flight Center oversees mission management, systems engineering, and safety, while Lockheed Martin Space in Littleton, Colorado, built the spacecraft. The Discovery Program, which funds Lucy, is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, under the agency’s Science Mission Directorate in Washington.

Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.