A Wobbling Relic: What Lucy Found at Asteroid Donaldjohanson
Lucy’s look at a small main-belt asteroid yields outsized clues about the solar system’s past.
TL;DR — NASA’s Lucy spacecraft revealed that asteroid Donaldjohanson is a tumbling, peanut-shaped fragment of an ancient collision roughly 150–155 million years ago — results published in Science on June 25, 2026 — sharpening clues about the solar system’s origins.
On June 25, 2026, a peanut-shaped asteroid revealed itself — wobbling, ancient, and full of clues.
The findings
NASA’s Lucy spacecraft, which flew past asteroid Donaldjohanson in April 2025, revealed it to be a tumbling, peanut-shaped fragment of an ancient collision, roughly 150–155 million years old — results published in Science on June 25, 2026. The asteroid rotates in a "tumbling" motion (an end-over-end period near 10.5 days plus a ~26.5-day rocking), and Lucy flew about 600–660 miles from it at roughly 30,000 mph.
| Property | Donaldjohanson | Bennu / Ryugu |
|---|---|---|
| Age | ~150–155 Myr | 1–2 billion yr |
| Rotation | Tumbling | Spinning-top |
| Location | Main belt | Near-Earth |
What they said
"Every subtle difference is another clue to our origin story." — Simone Marchi, Lucy deputy principal investigator & lead author, Southwest Research Institute
Why it matters
- A window into origins. Young collision fragments help reconstruct how the solar system evolved.
- Practice for the main act. Lucy’s real targets are Jupiter’s Trojan asteroids, a "fossil" population.
- Comparative planetology. Contrasts with Bennu and Ryugu sharpen models of asteroid formation.
FAQ
What did NASA’s Lucy discover at Donaldjohanson?
That the asteroid is a tumbling, peanut-shaped fragment of an ancient collision, roughly 150–155 million years old. The results were published in the journal Science on June 25, 2026, based on Lucy’s April 2025 flyby.
Why is the Lucy mission important?
Lucy is on its way to study Jupiter’s Trojan asteroids — a "fossil" population thought to preserve clues about the early solar system. The Donaldjohanson flyby was a science-rich rehearsal for those main targets.
Sources
Image: Asteroid Donaldjohanson (NASA Lucy) by NASA/Goddard/SwRI/Johns Hopkins APL — Public domain, via Wikimedia Commons.
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