Overview
- A peer-reviewed PNAS paper led by Tony Gargano of NASA Johnson and the Lunar and Planetary Institute uses Apollo regolith to read a long-term record of impactors.
- Triple oxygen isotope measurements isolate meteoritic material resistant to impact overprinting, indicating at least about 1% of the soil by mass is carbon-rich debris.
- Scaling the lunar signal to Earth’s roughly 20× higher impact rate yields a modeled contribution that explains only a small percent of ocean water.
- Co-author Justin Simon notes the findings constrain late meteoritic delivery as the dominant source of Earth’s oceans without ruling out a smaller contribution.
- Results reflect Apollo’s near-side equatorial sites, and Artemis-returned samples, including from polar cold traps, are expected to refine the Moon’s water record and resource outlook.