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2d ago

PNAS Study Finds Rare Water-Rich Meteorite Relics in Chang'e-6 Far-Side Samples

CI-like fragments identified by chemistry and triple-oxygen isotopes suggest volatile-bearing asteroids delivered material to the Earth–Moon system.

China's Chang'e-6 mission, the first sample return mission to the far side of the Moon, discovered extremely rare water-rich minerals.CN
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Overview

  • The research team identified seven microscopic, olivine-bearing clasts whose Fe/Mn ratios, NiO and CrO contents, and oxygen and silicon isotopes match CI carbonaceous chondrites.
  • Textural evidence shows the clasts are porphyritic impact-melt fragments that cooled rapidly after an asteroid strike on the lunar surface.
  • The discovery provides the first direct physical evidence that fragile CI chondrites struck the Moon and can persist in lunar regolith.
  • The authors estimate CI-like material may be much more common in the lunar impact record—potentially approaching 30 percent—underscoring biases in Earth’s meteorite collections.
  • The samples from the South Pole–Aitken Basin also underpin reports of two far-side basaltic episodes (~4.2 and ~2.8 billion years ago) and signs of a transient magnetic field near 2.8 billion years ago.