Graphs showing the interior evolution of Miranda diverging from that of Ariel.
The modeled interior evolution of Miranda diverges from that of Ariel, allowing Ariel to potentially retain a subsurface ocean while Miranda does not (lighter blue layer). These panels show time in millions of years on the x-axis (about 4.5 billion years total shown), with the present day on the right side. The colors indicate different temperatures and thus states of the material. The light orange and white (see also the 300 Kelvin (K) dashed line) show where icy material may be melted in the interior. In the case of Ariel, the interior may remain warm enough into the present to allow for liquid water under several hundred kilometers of ice. Credit: Castillo-Rogez et al. [2023], Figure 4 (modified)
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Planets

The large, icy Uranian moons have the potential to host subsurface oceans under their outer icy shells, both in the past and presently. Castillo-Rogez et al. [2022] consider a wide range of geochemical and geophysical parameters to model the interior evolution of the moons Miranda, Ariel, Umbriel, Titania, and Oberon.

Miranda and Ariel are notable for their striking, large-scale tectonic, and in some cases likely cryovolcanic, surface features. However, the study finds that Ariel and the other moons may have retained some interior liquid while Miranda likely has not. The authors found that the state of the present-day water in the interior of these moons, and the ability of a future spacecraft to detect liquid water, depends on the true compositions and structures of their interiors. A future spacecraft may be able to probe the interior of the moons directly during flybys by searching for magnetic field signatures, or it may reveal indirect evidence of subsurface oceans by imaging the geology of each moon.

Castillo-Rogez, J., Weiss, B., Beddingfield, C., Biersteker, J., Cartwright, R., Goode, A., et al. (2023). Compositions and interior structures of the large moons of Uranus and implications for future spacecraft observations. Journal of Geophysical Research: Planets, 128, e2022JE007432.

—Kelsi Singer, Associate Editor, JGR: Planets

Text © 2023. The authors. CC BY-NC-ND 3.0
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