Isotopic evidence of long-lived volcanism on Io

Katherine de Kleer; Ery C Hughes; Francis Nimmo; John Eiler; Amy E Hofmann; Statia Luszcz-Cook; Kathy Mandt

doi:10.1126/science.adj0625

Isotopic evidence of long-lived volcanism on Io

Science. 2024 May 10;384(6696):682-687. doi: 10.1126/science.adj0625. Epub 2024 Apr 18.

Authors

Katherine de Kleer¹, Ery C Hughes^{1

2}, Francis Nimmo³, John Eiler¹, Amy E Hofmann⁴, Statia Luszcz-Cook^{5

6

7}, Kathy Mandt⁸

Affiliations

¹ Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
² Earth Structure and Processes, Te Pū Ao | GNS Science, Avalon 5011, Aotearoa New Zealand.
³ Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
⁴ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
⁵ Liberal Studies, New York University, New York, NY 10023, USA.
⁶ Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA.
⁷ Department of Astrophysics, American Museum of Natural History, New York, NY 10024, USA.
⁸ NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

PMID: 38634676
DOI: 10.1126/science.adj0625

Abstract

Jupiter's moon Io hosts extensive volcanism, driven by tidal heating. The isotopic composition of Io's inventory of volatile chemical elements, including sulfur and chlorine, reflects its outgassing and mass-loss history and thus records information about its evolution. We used submillimeter observations of Io's atmosphere to measure sulfur isotopes in gaseous sulfur dioxide and sulfur monoxide, and chlorine isotopes in gaseous sodium chloride and potassium chloride. We find ³⁴S/³²S = 0.0595 ± 0.0038 (equivalent to δ³⁴S = +347 ± 86‰), which is highly enriched compared to average Solar System values and indicates that Io has lost 94 to 99% of its available sulfur. Our measurement of ³⁷Cl/³⁵Cl = 0.403 ± 0.028 (δ³⁷Cl = +263 ± 88‰) shows that chlorine is similarly enriched. These results indicate that Io has been volcanically active for most (or all) of its history, with potentially higher outgassing and mass-loss rates at earlier times.