SwRI-led Lucy mission survey of main belt asteroid Donaldjohanson imminent

(Press-News.org) SAN ANTONIO — April 15, 2025 —The Southwest Research Institute-led Lucy mission is preparing to survey the next target in its epic 4-billion-mile, 12-year, 11-asteroid tour. On April 20, 2025, NASA’s Lucy spacecraft will fly past the three-mile-wide main belt asteroid (52246) Donaldjohanson as a test run to the main event: visiting the never-before-explored Trojan asteroids in the Jupiter system.

For billions of years, these mysterious space rocks have been gravitationally trapped in two swarms leading and trailing Jupiter in orbit around the Sun, holding clues to the formation of our solar system. NASA’s Lucy spacecraft will be the first to study these ancient relics up close.

“While we can hardly wait to observe these fossils from the early solar system, the warm-up asteroids are proving to be quite interesting in their own right,” said SwRI’s Dr. Hal Levison, principal investigator of the Lucy mission. “Our 2022 flyby of Dinkinesh discovered Selam, a novel contact binary satellite of the main body. And ground-based observations suggest that Donaldjohanson is a peculiar, elongated object.”

Recent SwRI models indicate it may have formed about 150 million years ago when a larger parent asteroid broke apart.  Its orbit and spin properties have undergone significant evolution since.

“The data collected could provide independent insights on evolutionary processes based on its shape, surface geology and cratering history,” said SwRI’s Dr. Simone Marchi, Lucy deputy principal investigator. “Understanding the formation of Donaldjohanson could help explain its peculiarities.”

Lucy’s current target is a common asteroid type, composed of silicate rocks and perhaps some clays and organic matter. It’s likely a member of the Erigone collisional asteroid family, a group of asteroids on similar orbits created when a larger parent asteroid broke apart. The family originated in the inner main belt not 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.

“The flyby will answer some questions, because, as of now, Donaldjohanson’s characteristics appear very distinct from Bennu and Ryugu. The flyby may uncover unexpected connections,” Marchi said.

Donaldjohanson is named for the paleontologist who discovered Lucy, the fossilized skeleton of an early hominin found in Ethiopia in 1974 and the inspiration for the name of the Lucy mission. Just as the Lucy fossil provided unique insights into the origin of humanity, the Lucy mission promises to expand 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.

“Encounters with main belt asteroids not only provide a close-up view of those bodies but also allow us to perform an end-to-end test of the spacecraft’s systems before we get to the Trojans,” Levison said. “The instruments aboard Lucy will allow unprecedented precision in mapping these relics, which are effectively fossils of the planet formation process. The vital clues to deciphering the history of our solar system, including our home planet.”

Lucy’s principal investigator is based out of Southwest Research Institute’s Solar System Science and Exploration Division in Boulder, Colorado. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering and safety and mission assurance. Lockheed Martin Space in Littleton, Colorado, built the spacecraft. Lucy is the 13th mission in NASA’s Discovery Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Discovery Program for the agency’s Science Mission Directorate in Washington.

Learn more about this encounter here: NASA’s Scientific Visualization Studio.

For more information, visit https://www.swri.org/markets/earth-space/space-research-technology/space-science/planetary-science.

END