Bowing
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Planets
Carbon dioxide (CO2) ice is known to be present on the surfaces of the Uranian moons Ariel, Umbriel, Titania, and Oberon. More CO2 is found on the trailing hemispheres of these phase-locked moons compared to their leading hemispheres, and a radial trend is also noted, with the inner moon Ariel having the strongest CO2 signature. It has thus been hypothesized that the CO2 is a product of radiolytic bombardment.
Menten et al. [2024] test theories of CO2 origin on Ariel by modeling the transport and sublimation of CO2 across the surface. The high obliquity of the Uranus system means that the subsolar point on these moons varies between near the south pole and near the north pole on seasonal timescales (one Uranus year is about 84 Earth years). The authors find that CO2 ice can migrate on timescales of just a few Uranian years, and that it will tend to migrate towards Ariel’s equator and away from the poles, uniformly in longitude.
The authors find that canyons, seen on the surface of Ariel in Voyager 2 images, could act as cold traps for CO2 migrating across Ariel’s surface. Given that more CO2 is observed on Ariel’s trailing hemisphere, the authors conclude that CO2 is either actively produced exogenically through radiolysis, is from an endogenic source that led to stable ice deposits in canyons on the trailing hemisphere, or that both sources are contributing to the observed distribution. A future Uranus orbiter could distinguish between these ideas.
Citation: Menten, S. M., Sori, M. M., Bramson, A. M., Nordheim, T. A., & Cartwright, R. J. (2024). Volatile transport on ariel and implications for the origin and distribution of carbon dioxide on Uranian moons. Journal of Geophysical Research: Planets, 129, e2024JE008376. https://doi.org/10.1029/2024JE008376
—Amanda Hendrix, Editor-in-Chief, JGR: Planets
