Nasa spacecraft observes peanut-shaped asteroid during April 2025 flyby

Nasa's Lucy spacecraft flew past asteroid Donaldjohanson on April 20, 2025, and recorded images showing an elongated, peanut-like form with two lobes connected by a narrower neck. The asteroid measures about half a mile in diameter and rotates around two axes, producing a tumbling motion as it travels through the solar system.

Researchers at the Southwest Research Institute analyzed the data and published their findings in the journal Science.

Asteroid composition and origin The flyby detected iron-rich clay minerals that formed near liquid water. Scientists concluded the asteroid likely consists of fragments from a larger, carbon- and water-rich body that broke apart after a collision in the main asteroid belt 155 million years ago.

Mission testing and future observations The Donaldjohanson encounter served as a test of Lucy's instruments and procedures ahead of its planned visits to the Trojan asteroids near Jupiter. Those asteroids are thought to preserve material from the early solar system.

"This encounter gave us an opportunity to test our instruments and our procedures to make sure we are ready when we get to Jupiter's Trojans," said the study's lead author. The mission aims to gather data that could revise current models of solar system formation.