Io’s tidal response precludes a shallow magma ocean
Io experiences tidal deformation as a result of its eccentric orbit around Jupiter, which provides a primary energy source for Io's continuing volcanic activity and infrared emission<sup>1</sup>. The amount of tidal energy dissipated within Io is enormous and has been suggested to support the large-scale melting of its interior and the formation of a global subsurface magma ocean. If Io has a shallow global magma ocean, its tidal deformation would be much larger than in the case of a more rigid, mostly solid interior<sup>2</sup>. Here we report the measurement of Io's tidal deformation, quantified by the gravitational tidal Love number k<sub>2</sub>, enabled by two recent flybys of the Juno spacecraft. By combining Juno<sup>3,4</sup> and Galileo<sup>5-7</sup> Doppler data from the NASA Deep Space Network and astrometric observations, we recover Re(k<sub>2</sub>) of 0.125 ± 0.047 (1σ) and the tidal dissipation parameter Q of 11.4 ± 3.6 (1σ). These measurements confirm that a shallow global magma ocean in Io does not exist and are consistent with Io having a mostly solid mantle<sup>2</sup>. Our results indicate that tidal forces do not universally create global magma oceans, which may be prevented from forming owing to rapid melt ascent, intrusion and eruption<sup>8,9</sup>, so even strong tidal heating-such as that expected on several known exoplanets and super-Earths<sup>10</sup>-may not guarantee the formation of magma oceans on moons or planetary bodies.
Authors
- D. J. Stevenson (ORCID: https://orcid.org/0000-0001-9432-7159)
- A. Mura (ORCID: https://orcid.org/0000-0002-4552-4292)
- Ryunosuke Akiba (ORCID: https://orcid.org/0000-0002-2681-3195)
- Luis Gomez Casajus (ORCID: https://orcid.org/0000-0002-7972-4006)
- Daniele Durante (ORCID: https://orcid.org/0000-0002-7888-3021)
- S. Levin (ORCID: https://orcid.org/0000-0003-2242-5459)
- Marco Zannoni (ORCID: https://orcid.org/0000-0002-4151-9656)
- Andrea Magnanini (ORCID: https://orcid.org/0000-0001-6761-1429)
- J. T. Keane (ORCID: https://orcid.org/0000-0002-4803-5793)
- Dustin Buccino (ORCID: https://orcid.org/0000-0002-2888-5918)
- L. Iess (ORCID: https://orcid.org/0000-0002-6230-5825)
- A. Ermakov (ORCID: https://orcid.org/0000-0002-7020-7061)
- J. E. P. Connerney (ORCID: https://orcid.org/0000-0001-7478-6462)
- S. J. Bolton (ORCID: https://orcid.org/0000-0002-9115-0789)
- F. Nimmo (ORCID: https://orcid.org/0000-0003-3573-5915)
- Ryan S. Park (ORCID: https://orcid.org/0000-0001-9896-4585)
- W. B. McKinnon
- Marzia Parisi (ORCID: https://orcid.org/0000-0003-4064-6634)
- Benjamín Idini (ORCID: https://orcid.org/0000-0002-2697-3893)
- Paolo Tortora (ORCID: https://orcid.org/0000-0001-9259-7673)
- R. A. Jacobson
Institutions
- California Institute of Technology (US)
- Southwest Research Institute (US)
- Goddard Space Flight Center (US)
- Jet Propulsion Laboratory (US)
- Vaughn College of Aeronautics and Technology (US)
- University of California, Santa Cruz (US)
- Washington University in St. Louis (US)
- Institute for Space Astrophysics and Planetology (IT)
- Research Centre for Cereal and Industrial Crops (IT)
- Sapienza University of Rome (IT)
- National Institute for Astrophysics (IT)
- University of Bologna (IT)
- Stanford University (US)
Publication Details
- Journal
- Nature
- Published
- 2024-12-12
- DOI
- https://doi.org/10.1038/s41586-024-08442-5
- Citations
- 31
- Primary Topic
- Astro and Planetary Science
- Type
- article
- Field-Weighted Citation Impact
- 10.28