NASA’s Lucy spacecraft has identified asteroid 3548 Donaldjohanson as a “peanut‑shaped” body that exhibits a slow wobble and bears chemical signatures of water from the early solar system, scientists reported Thursday.
The Lucy flyby, part of a mission to study Jupiter‑trojan asteroids, captured high‑resolution images and spectroscopic data of the 2‑kilometer‑wide object. Analysis of the shape suggests it was formed by a violent collision that broke apart a larger parent body, after which solar radiation pressure — the subtle force of sunlight — has gradually altered its spin, causing a detectable precession or wobble.
Spectral measurements revealed absorption features consistent with hydrated minerals, indicating that water‑bearing compounds were present on the asteroid’s surface billions of years ago. The presence of these minerals on a Jupiter‑trojan asteroid provides a rare clue to how water may have been distributed throughout the early solar system.
“Donaldjohanson is a relic that has survived since the era of planet formation,” said a NASA scientist involved in the mission. “Its shape, spin state, and water signatures together make it a valuable laboratory for understanding the processes that shaped our planetary neighborhood.”
The discovery adds to Lucy’s growing catalog of observations that challenge traditional views of Trojan asteroids as inert, rocky remnants. By confirming that at least some of these bodies contain hydrated minerals, the findings support theories that water and organic compounds could have been delivered to the inner planets via migrating planetesimals.
Analysis: The wobble detected on Donaldjohanson illustrates how even weak forces like solar radiation can influence small bodies over long timescales, reshaping their rotational dynamics. Coupled with the detection of hydrated minerals, the asteroid serves as a tangible record of the solar system’s volatile inventory. Future missions may target similar objects to further map the distribution of water across different asteroid populations, refining models of planetary accretion and the delivery of life‑supporting ingredients to Earth.
Sources
Science Daily, “NASA’s Lucy finds a wobbling peanut-shaped asteroid with signs of ancient water,” June 24, 2026, https://www.sciencedaily.com/releases/2026/06/260624025455.htm
Source: Science Daily – Original article
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Story synopsis gathered from: Science Daily — source
