CAREER: GLOW: The Long-Term Histories of Geologically Active Solar System Moons from Isotope Geochemistry

The investigator, Dr. Katherine de Kleer of the California Institute of Technology, has developed experiments to measure gases released from the interiors of bodies in the outer Solar System. When the Earth and our planet neighbors are viewed within the Solar System today, we see only a snapshot of their full lifetimes. In order to put this snapshot in context, the investigator would like to understand their long-term histories, or how they got to be the way they are today. On worlds, like Earth, that have active geology (plate tectonics, volcanism etc), the signatures that we might use to study their past have been erased. Measurements of chemical elements with slightly different masses provide a rare opportunity to study the more distant histories of planets. With new telescopes, these measurements are only now becoming possible for the outer part of the Solar System. The investigator and her research group will use new telescope observations study the evolution of Solar System moons and dwarf planets. By combining these observations with models, this work will advance understanding of the heat flow and mass loss histories of these worlds. The program will involve students from undergraduate to PhD level, as well as postdoctoral scholars. It will additionally train young scientists in producing innovative, interactive science content for the public, tailored to a range of settings. This project applies established techniques in isotope geochemistry to geologically-active moons observed with astronomical methods, thus bridging the disciplines of astronomy, geology, and geochemistry. It will specifically provide insight into: the longevity of tidal heating at the galilean satellites; the mass loss and surface-interior exchange processes at Enceladus; and the formation and migration histories of captured moons. The project will utilize new observations from the Atacama Large (sub-)Millimeter Array, which will be interpreted using models that will consider all isotope reservoirs and exchange rates for the relevant species, enabling robust bounds on formation and evolutionary scenarios. The results will address fundamental open questions about these objects, and will establish the abiotic isotope background for Solar System moons, an important first step towards using isotopes as biosignatures. Co-funding was provided by the Division of Astronomy and Division of Earth Sciences through a partnership focused on Geoscience Lessons for and from Other Worlds (GLOW). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.