NASA’s Lucy spacecraft captured stunning images of the asteroid Donaldjohanson during a close flyby on April 20, revealing a peculiar elongated contact binary with a narrow, ice-cream-cone-like neck connecting its two lobes. The encounter, which occurred approximately 600 miles from the asteroid, marks Lucy’s second asteroid observation and provides new insights into the solar system’s formative processes.
The asteroid, formed about 150 million years ago, displayed large brightness variations over a 10-day period in prior observations, hinting at its unusual structure. Initial images from Lucy’s L’LORRI imager confirmed expectations of a contact binary—formed when two smaller bodies collide—but surprised scientists with the complex geometry of its narrow neck. “Asteroid Donaldjohanson has strikingly complicated geology,” said Hal Levison, principal investigator for Lucy at Southwest Research Institute, Boulder, Colorado. “As we study the complex structures in detail, they will reveal important information about the building blocks and collisional processes that formed the planets in our Solar System.”
Preliminary analysis suggests Donaldjohanson is larger than previously estimated, measuring about 5 miles long and 2 miles wide at its widest point.The asteroid’s size exceeds the L’LORRI imager’s field of view, meaning the full structure isn’t visible in the first high-resolution images. The Lucy team expects to receive the remaining data within a week, which will provide a clearer picture of the asteroid’s shape. Additional data from Lucy’s L’Ralph color imager, infrared spectrometer, and L’TES thermal infrared spectrometer will be analyzed over the coming weeks to further characterize the asteroid’s composition and surface.
A Rehearsal for Future Discoveries
Unlike Lucy’s primary targets, the Jupiter Trojan asteroids, Donaldjohanson is not a core science objective. The flyby served as a full dress rehearsal for the mission, following a successful systems test with the asteroid Dinkinesh in 2023. During the Donaldjohanson encounter, the team conducted dense observations to maximize data collection, testing the spacecraft’s instruments and operational capabilities.
“These early images of Donaldjohanson are again showing the tremendous capabilities of the Lucy spacecraft as an engine of discovery,” said Tom Statler, program scientist for the Lucy mission at NASA Headquarters in Washington. “The potential to really open a new window into the history of our solar system when Lucy gets to the Trojan asteroids is immense.”
Lucy will spend most of 2025 traveling through the main asteroid belt, with its next major milestone being a flyby of the Jupiter Trojan asteroid Eurybates in August 2027. The mission, the 13th in NASA’s Discovery Program, aims to study the Trojan asteroids to uncover clues about the solar system’s early evolution.
Mission Management and Collaboration
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, oversees mission management, systems engineering, and safety assurance, and developed the L’Ralph instrument. The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, designed and built the L’LORRI imager, while Arizona State University created the L’TES spectrometer. Lockheed Martin Space in Littleton, Colorado, constructed the spacecraft and designed its trajectory, with flight operations supported by Goddard and KinetX Aerospace. The Southwest Research Institute, headquartered in San Antonio, leads the science team, observation planning, and data processing under Hal Levison’s direction.
The Lucy mission continues to demonstrate the power of robotic exploration, offering a glimpse into the solar system’s distant past through its detailed study of ancient asteroids.
