NASA's Lucy Spacecraft Prepares for Astounding Encounter with Asteroid Donaldjohanson

NASA's Lucy spacecraft is poised for a significant milestone as it approaches asteroid (52246) Donaldjohanson for a flyby scheduled on April 20, 2025. This encounter marks the second asteroid visit in Lucy's 12-year mission, following its 2023 flyby of asteroid Dinkinesh and its moonlet Selam.

Launched on October 16, 2021, the Lucy mission aims to explore a record-breaking number of asteroids, including three in the main asteroid belt and eight Trojan asteroids that share Jupiter's orbit around the Sun. These Trojan asteroids are considered "fossils" of planetary formation, offering insights into the early solar system. The mission is named after the fossilized skeleton of an early hominin, symbolizing its goal to uncover the "fossils" of planetary formation.

Asteroid Donaldjohanson, approximately 3.9 kilometers (2.4 miles) in diameter, resides in the main asteroid belt between Mars and Jupiter. It is a member of the Erigone collisional asteroid family, believed to have formed about 150 million years ago from the fragmentation of a larger parent asteroid. Over time, Donaldjohanson's orbit and rotation have evolved due to non-gravitational forces such as the Yarkovsky and YORP effects, which result from thermal radiation and solar radiation pressure, respectively.

During the upcoming flyby, Lucy will pass within 960 kilometers (596 miles) of Donaldjohanson. The spacecraft's instruments will collect data on the asteroid's shape, surface geology, and cratering history. This information is expected to provide insights into the processes that have influenced Donaldjohanson's evolution and contribute to our understanding of the early solar system.

"Based on ground-based observations, Donaldjohanson appears to be a peculiar object," said Simone Marchi, deputy principal investigator for Lucy at the Southwest Research Institute. "Understanding the formation of Donaldjohanson could help explain its peculiarities.”

The flyby also serves as a critical rehearsal for Lucy's future encounters with the Trojan asteroids. By testing the spacecraft's systems and procedures during this encounter, the mission team aims to ensure the success of subsequent flybys. The data collected from Donaldjohanson will help refine models of asteroid formation and evolution, enhancing our comprehension of the processes that shaped the solar system.

As Lucy continues its journey, the mission promises to shed light on the building blocks of planetary formation, offering a window into the distant past of our cosmic neighborhood.