Strong Tidal Dissipation at Uranus?

Abstract

Geophysical estimates of paleo heat fluxes on the Uranian moons Miranda and Ariel are in the range of 25–75 mW m−2. For a canonical Uranus dissipation factor Q = 18,000, expected equilibrium tidal heating rates for these satellites are less than 6 mW m−2. At least for Ariel, this order-of-magnitude discrepancy can be resolved by positing a low Uranus Q ≈ 103 in the recent past and at the present day. Such a low Q (high dissipation) can be reconciled with an ancient origin of the Uranian satellites if Q is time-dependent, as exemplified by the “resonance-locking” hypothesis, and provides an additional constraint on the interior structure of the planet. A Q of 103 implies present-day migration rates for Miranda and Ariel of 5 and 11 cm yr−1, respectively, potentially detectable via astrometry.

Uranus Orbiter and Probe: A Radio Science Investigation to Determine the Planet’s Gravity Field, Depth of the Winds, and Tidal Deformations

“…Additionally, this theory accurately predicts levels of tidal dissipation consistent with calculations derived from the orbits of Uranus's main satellites. On the other hand, a recent work by Nimmo (2023) argues that geologic evidence suggests a much more dissipative Uranus, perhaps through the action of resonance locking between moon orbits and Uranus normal modes, as seems to be the case at Saturn.…”