NASA’s Lucy spacecraft captures images of asteroid Donaldjohanson during flyby

On April 20, 2025, at 13:51 EDT (17:51 UTC), NASA’s Lucy spacecraft conducted a flyby of asteroid Donaldjohanson in the main asteroid belt between Mars and Jupiter. The spacecraft passed within 960 km (600 miles), capturing images from a distance of 1 100 km (660 miles). This marked Lucy’s second asteroid encounter, following its 2023 flyby of asteroid Dinkinesh.

The asteroid, named after the anthropologist who discovered the Lucy hominin fossil, measures around 8 km (5 miles) in length and 3.5 km (2 miles) at its widest point. Its shape, classified as an elongated contact binary, includes two lobes connected by a narrow neck with an irregular structure.

Images captured by the Lucy Long-Range Reconnaissance Imager (L’LORRI) include a timelapse recorded every 2 seconds, beginning at 13:50 EDT (17:50 UTC). Additional instruments, L’Ralph and L’TES, collected data on surface composition and thermal properties. Transmission to Earth began immediately, with full datasets expected within one week.

The flyby was a preparatory exercise for Lucy’s primary mission to study Jupiter’s Trojan asteroids. The next target, Eurybates, is scheduled for August 2027.

Launched in October 2021, Lucy aims to explore primitive asteroids to improve understanding of the early solar system. The Donaldjohanson flyby tested the spacecraft’s navigation and imaging systems for future flybys.

Donaldjohanson is estimated to have formed about 150 million years ago from the breakup of a larger parent body. Early data shows slow rotation, with apparent motion in images resulting from the spacecraft’s flyby dynamics. Brightness variations observed during a 10-day period before the flyby showed a complex structure, which is now confirmed by the images.

Analysis of the collected data will continue, focusing on refining measurements of the asteroid’s dimensions and surface features. The contact binary structure may offer insights into collisional processes in the early solar system. Scientists expect that L’Ralph and L’TES data will reveal more about the asteroid’s composition in the coming weeks.

Compared to the 2023 Dinkinesh flyby, Donaldjohanson’s larger size and distinct morphology expand the range of asteroid structures observed by Lucy. Optical navigation images taken between February and April 2025 ensured accurate positioning for the flyby and supported the mission’s operational strategy.

The Lucy mission, scheduled to last 12 years, will visit eight Trojan asteroids to study their role as remnants of early planetary formation. The Donaldjohanson flyby, although not a primary science target, provided important operational experience. The spacecraft’s health was confirmed after the flyby, ensuring readiness for future encounters.

References:

¹ NASA’s Lucy Spacecraft Images Asteroid Donaldjohanson – NASA – April 21, 2025

² NASA’s Lucy Spacecraft Completes Asteroid Donaldjohanson Flyby – NASA – April 20, 2025

³ NASA’s Lucy Spacecraft Takes Its 1st Images of Asteroid Donaldjohanson – NASA – February 25, 2025

Reet Kaur

I’m a science journalist and researcher at The Watchers, contributing to the Epicenter edition, where I cover peer-reviewed scientific research and emerging discoveries across Earth and space sciences. With a background in astronomy and a passion for environmental science, I’ve worked in shark and coral conservation in Fiji, conducting reef and shark-behavior research, contributing to mangrove restoration, and earning PADI Open Water and Coral Reef Certifications. I bring a blend of scientific rigor and storytelling to illuminate the discoveries shaping our planet and beyond.

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