Even a relatively small asteroid can have a surprisingly dramatic history. During a close flyby of the asteroid Donaldjohanson, NASA’s Lucy spacecraft discovered an oddly shaped world that wobbles through space, bears scars from an ancient collision, and even preserves evidence that liquid water briefly existed on its parent body long ago.

The asteroid formed about 155 million years ago when fragments from a violent impact slowly came back together. Since then, sunlight has steadily altered its rotation through a subtle but powerful process, leaving behind clues to its long and eventful evolution.

Lucy’s Close Encounter With Donaldjohanson
On April 20, 2025, Lucy flew within 650 miles of Donaldjohanson while traveling through the main asteroid belt on its way to the Jupiter Trojan asteroids. The spacecraft captured the first detailed images and scientific measurements of this previously unexplored object.

Rather than rotating around a single axis like most planets and asteroids, Donaldjohanson was found to have a much more complicated motion involving two separate rotational movements. The flyby also revealed its distinctive peanut-like shape along with numerous craters and ridges covering its surface.

The encounter served as a full-scale rehearsal before Lucy begins exploring the Trojan asteroids, starting with its flyby of Eurybates on Aug. 12, 2027. Everything aboard the spacecraft operated as planned, while scientists gained an unexpected opportunity to compare Donaldjohanson with two better-known asteroids, Bennu and Ryugu. Those two bodies have similar compositions but followed very different evolutionary paths after their formation.

The Lucy team’s initial findings were published June 18 in the journal Science.