Solar wind contributions to Earth’s oceans

Luke Daly, Martin R. Lee, Lydia J. Hallis, Hope A. Ishii, John P. Bradley, Phillip A. Bland, David W. Saxey, Denis Fougerouse, William D.A. Rickard, Lucy V. Forman, Nicholas E. Timms, Fred Jourdan, Steven M. Reddy, Tobias Salge, Zakaria Quadir, Evangelos Christou, Morgan A. Cox, Jeffrey A. Aguiar, Khalid Hattar, Anthony MonterrosaLindsay P. Keller, Roy Christoffersen, Catherine A. Dukes, Mark J. Loeffler, Michelle S. Thompson

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


The isotopic composition of water in Earth’s oceans is challenging to recreate using a plausible mixture of known extraterrestrial sources such as asteroids—an additional isotopically light reservoir is required. The Sun’s solar wind could provide an answer to balance Earth’s water budget. We used atom probe tomography to directly observe an average ~1 mol% enrichment in water and hydroxyls in the solar-wind-irradiated rim of an olivine grain from the S-type asteroid Itokawa. We also experimentally confirm that H+ irradiation of silicate mineral surfaces produces water molecules. These results suggest that the Itokawa regolith could contain ~20 l m3 of solar-wind-derived water and that such water reservoirs are probably ubiquitous on airless worlds throughout our Galaxy. The production of this isotopically light water reservoir by solar wind implantation into fine-grained silicates may have been a particularly important process in the early Solar System, potentially providing a means to recreate Earth’s current water isotope ratios.

Original languageEnglish (US)
Pages (from-to)1275-1285
Number of pages11
JournalNature Astronomy
Issue number12
StatePublished - Dec 2021

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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