NASA’s Lucy spacecraft has unveiled unexpected details about the asteroid Donaldjohanson during its flyby last year. Observations reveal that this asteroid, barely 4 kilometers in diameter, possesses a bilobate, peanut-like shape and exhibits an unstable rotational motion, or "wobble." These findings suggest a more complex geological and dynamic history than anticipated for a body of its size in the main asteroid belt.

Donaldjohanson is a C-type, carbon-rich asteroid and part of the Erigone asteroid family, which originated from the fragmentation of a larger parent body approximately 155 million years ago. The bilobate shape is consistent with an origin from the accumulation of two separate objects that collided at low speed, or from the breakup and subsequent re-accretion of a single body. The wobble, on the other hand, could be the result of asymmetric impacts or the ejection of material, which would have altered its angular momentum.

The Lucy mission is designed to study Jupiter's Trojan asteroids, but Donaldjohanson was an additional target in the main belt. The data obtained by Lucy, including high-resolution images and spectroscopic measurements, will allow scientists to better understand the formation and evolution processes of asteroids, as well as the dynamics of small bodies in the early solar system. The characterization of these objects is crucial for reconstructing the history of collisions and the distribution of materials in the protoplanetary disk.