Washington: NASA's Lucy spacecraft has uncovered striking new details about the asteroid Donaldjohanson, revealing that the oddly shaped space rock tumbles through space on two axes and may preserve evidence of ancient water from the early solar system.
The spacecraft flew within 960 kilometres of the asteroid on April 20, 2025, capturing its first close-up images and scientific data. Observations showed Donaldjohanson has a distinctive peanut-like shape covered with craters and ridges. Scientists also found that, unlike most asteroids and planets that rotate around a single axis, the asteroid wobbles with a rare two-axis rotation.
Researchers detected iron-rich clay minerals on its surface, indicating that liquid water may once have existed on the asteroid or its larger parent body. Similar magnesium-rich clay minerals have previously been identified on the asteroids Bennu and Ryugu, suggesting prolonged exposure to water over millions of years before those bodies fragmented.
Scientists believe Donaldjohanson's unusual rotation has gradually developed through the YORP effect, a process in which uneven heat radiated from the Sun creates tiny forces that can alter an asteroid's spin over time, either accelerating or slowing its rotation.
The asteroid, formed after a violent collision about 155 million years ago, lies in the main asteroid belt between Mars and Jupiter. It is named after anthropologist Donald Johanson, who discovered the famous fossil "Lucy." The spacecraft, built by Lockheed Martin Space and operated under NASA's Discovery Program, encountered Donaldjohanson while travelling toward the Jupiter Trojan asteroids, its primary scientific destination.