Isotopic evidence of long-lived volcanism on Io.

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.