Features on asteroid visited by Lucy spacecraft given official names

Surface features on asteroid 52246 Donaldjohanson, as identified by the Southwest Research Institute-led Lucy mission, have been given official names by the International Astronomical Union (IAU). The surface features of the carbonaceous asteroid will be named for significant paleoanthropological sites and discoveries. The NASA Lucy spacecraft flew past the asteroid on April 20, 2025.

“Visiting a new world for the first time is very exciting. Just as the explorers used to do here on Earth, when we come upon a new celestial body, we like to map the landscape and name its most interesting features,” said SwRI’s Dr. Simone Marchi, who serves as deputy principal investigator for the Lucy mission. “At first glance, the asteroid Donaldjohanson resembles a peanut and includes many interesting features.”

Donaldjohanson is approximately 8 kilometers (5 miles) long and 3.5 kilometers (2.2 miles) wide. SwRI-led modeling indicates that it may have formed about 155 million years ago when a larger parent asteroid broke apart. Its namesake, paleoanthropologist Donald Johanson, discovered the fossilized skeleton of an early human ancestor, or hominin, in Ethiopia in 1974 and named it Lucy. The Lucy mission is, in turn, named after this discovery. It is the only asteroid so far to be visited while its namesake is still living.

Naming features on planetary bodies makes it easier for scientists to model and clearly communicate new discoveries about these objects. The IAU governs the naming of planetary bodies and their features, only approving names when they have a special scientific interest or are useful to the scientific community at large.

“When it came time to designate the features on the asteroid Donaldjohanson, the Lucy mission team had an interesting decision on our hands,” Marchi said. “We chose names honoring notable ancestors and paleoanthropological locations found across the globe, something we found in keeping with the spirit of the person the asteroid is named after and his career.”

The asteroid’s smaller lobe is called the Afar lobe after the Ethiopian region where Lucy and other human ancestor fossils were found. The large lobe is named the Olduvai lobe after a Tanzanian river gorge. The neck connecting the two lobes was named after the Windover Archeological Site near Cape Canaveral, Florida, where Lucy was launched in 2021. This is the first time the IAU has recognized an asteroid’s neck as an officially named feature. Additional features include two smooth areas on the neck named the Hadar region, after the site of the Lucy fossil’s discovery, and the Minatogawa region, where the oldest known hominins in Japan were found.

The SwRI-led Lucy mission visited Donaldjohanson earlier this year, at a closest approach range of approximately 960 kilometers (596 miles) as a test of its instruments and abilities ahead of its flyby of the Jupiter Trojan asteroid Eurybates in 2027, which is the first of its primary science targets. Over its 12-year mission, Lucy will visit and observe 11 asteroids on its tour of the Trojan asteroids that lead and trail Jupiter. The mission aims to provide vital clues for deciphering the history of the solar system.