Overview
- The Lucy spacecraft, which flew within about 600 miles of asteroid 52246 Donaldjohanson on April 20, 2025, returned high‑resolution images and spectra used in a Science paper published June 18, 2026.
- Close images show Donaldjohanson is a bilobed, peanut‑shaped body with a narrow smooth neck linking two cratered lobes, implying it formed by the re‑accumulation of fragments.
- Counting craters across the surface produced a collisional age near 155 million years, matching the timing of a catastrophic breakup that created the Erigone asteroid family.
- Infrared spectra detected iron‑bearing phyllosilicates similar to those in carbonaceous meteorites, indicating limited aqueous alteration in the parent body and early presence of liquid water.
- Lucy’s Donaldjohanson encounter served as an operational and scientific dress rehearsal for the primary Trojan asteroid visits that begin with Eurybates and Queta in August 2027.