NASA's Lucy spacecraft has revealed that the asteroid Donaldjohanson is a wobbling, peanut-shaped relic, an elongated body that scientists say was born from a violent collision and slowly reshaped over billions of years in the main asteroid belt.
A close look at an old survivor
Lucy captured detailed views of Donaldjohanson during a flyby, showing a strikingly irregular object with two lobes joined at a narrow neck. The distinctive shape suggests a complex history rather than a simple, intact chunk of rock, making the asteroid a valuable record of processes that shaped the early Solar System.
Born from a collision
The asteroid appears to be a fragment produced when a larger parent body was shattered long ago. Over time, gentle forces and its own rotation gradually molded the debris into the elongated form seen today, complete with a slow wobble in its spin.
- Donaldjohanson shows a two-lobed, peanut-like structure.
- It likely formed from the breakup of a larger asteroid.
- Slow reshaping and rotation produced its elongated profile.
- The flyby served as a rehearsal for Lucy's main mission.
Why Lucy is visiting asteroids
Lucy's primary targets are the Trojan asteroids that share Jupiter's orbit, thought to be pristine leftovers from the era when the planets formed. Encounters with main-belt objects like Donaldjohanson let the mission test its instruments and add to the growing catalog of small-body shapes and histories.
Fossils of the early Solar System
Asteroids preserve material that has changed little since planets first assembled, making them time capsules for researchers. By studying how bodies like Donaldjohanson formed and evolved, scientists can piece together the collisions and gentle sculpting that shaped the belt over billions of years.
What the flyby adds
The encounter demonstrates Lucy's ability to image small, fast-moving targets in detail and returns a fresh example of the surprising diversity among asteroids. Each new shape and structure helps refine models of how such objects break apart and reassemble.
- The mission builds a library of asteroid shapes and histories.
- Findings inform models of collisions in the asteroid belt.
- The flyby prepares Lucy for its Trojan asteroid encounters.
Turning a brief encounter into data
Flybys are demanding because the spacecraft sweeps past its target at high speed, giving instruments only a narrow window to capture images and measurements. To make the most of it, Lucy's cameras track the asteroid as the craft races by, building up detailed views of its shape, surface, and rotation. Engineers use encounters like this one to fine-tune pointing and timing, lessons that will pay off when the mission reaches the more scientifically prized Trojan asteroids further along its route.
Lucy will continue its long journey toward Jupiter's orbit, where its most anticipated science awaits at the Trojans. But the study of Donaldjohanson already shows how much a single, well-timed flyby can reveal, turning a distant point of light into a detailed portrait of an ancient, battered survivor from the dawn of the Solar System.