June 25, Washington. NASA’s Lucy spacecraft, while exploring the history of the universe, has discovered an unusual almond-shaped asteroid that wobbles as it moves. Named ‘DonaldJohanson,’ this asteroid has proven to be a crucial link in revealing secrets about ancient water, cosmic collisions, and the origins of the solar system. According to scientists, around 155 million years ago, fragments from a catastrophic space collision gradually came together under gravity to form this asteroid.
During its close flyby on April 20, 2025, at a distance of 650 miles from the asteroid, Lucy captured images and scientific measurements that were published in the journal Science on June 18. Although it appears to spin normally when viewed from Earth, Lucy’s data reveal that the asteroid rotates in an unusual manner, similar to a “spinning top.” It completes one spin every 10.5 days while also rocking back and forth along its long axis every 26.5 days.
Consisting of two large lobes connected by a narrow “neck” region, this almond-shaped asteroid’s form has been gradually altered over time due to subtle forces exerted by sunlight. The sun’s radiation heats the asteroid, causing it to emit infrared radiation, which generates slight pushes that slow its rotation over millions of years. As its rotation slows, loosely bound rocks and debris shift inward, softening the edges of its craters.
The mission’s most significant discovery is the presence of iron-rich soil minerals on the surface of DonaldJohanson. Such minerals form only in the presence of liquid water, confirming that water existed on the asteroid for a brief period in the past. This finding contrasts with asteroids like Bennu and Ryugu, where magnesium-rich soils suggest water persisted for millions of years.
Named after the famous human ancestor fossil “Lucy,” this space mission is advancing studies of Jupiter’s Trojan asteroids. The successful study of DonaldJohanson serves as an important rehearsal for the Lucy mission, enhancing our understanding of the formation and evolutionary history of planetary bodies within the solar system in the coming years.
