Titan's spin state as a constraint on tidal dissipation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39908389.
- Also identified by DOI 10.1126/sciadv.adl4741 and PMC identifier 11797539.
- Licence recorded as CC BY-NC.
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Abstract
Tidal dissipation in satellites affects their orbital and rotational evolution and their ability to maintain subsurface oceans. However, a satellite's dissipation rate, parameterized by <i>k</i><sub>2</sub><i>/Q</i>, is hard to measure and is only known for the Moon and Io. Here, we use Titan's measured departure from its expected rotation state to infer <i>k</i><sub>2</sub><i>/Q</i> and its boundary layer dissipation parameter <i>K/C</i><sub>s</sub>. Over the likely range of ocean and ice shell thicknesses, we infer a <i>K</i>/<i>C</i><sub>s</sub> of 6.3 × 10<sup>-14</sup> s<sup>-1</sup> to 2.4 × 10<sup>-10</sup> s<sup>-1</sup>, a <i>k</i><sub>2</sub><i>/Q</i> of 0.058 to 0.12, and a minimum dissipation factor <i>Q ≈ 5</i>. Titan's dissipation parameters are one to two orders of magnitude larger than the Moon's and suggest an interior with a low effective viscosity. Titan's dissipation rate implies that its eccentricity and inclination are damping rapidly, consistent with an excitation within the last ~350 Myr. The forthcoming Dragonfly lander could measure Titan's tidal response, and JUICE could use our approach to determine Ganymede's <i>k</i><sub>2</sub><i>/Q</i>.