Searching for Subsurface Oceans on the Moons of Uranus Using Magnetic Induction

Weiss, B. P.; Biersteker, John B.; Colicci, Vittorio; Goode, Allison; Castillo‐Rogez, Julie; Petropoulos, Anastassios E.; Balint, Tibor S.

doi:10.1029/2021gl094758

Cited by 28 publications

(28 citation statements)

References 49 publications

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“…An orbiter with a visible/near-infrared mapping spectrometer would allow us to determine whether NH 3 -bearing species are spatially associated with Ariel's chasmata, double ridges, and other geologic features and would provide insight into the ages of geologic events and interior compositions (Cartwright et al 2020(Cartwright et al , 2021. Furthermore, a magnetometer on an orbiter could search for induced magnetic fields in Ariel, a key diagnostic trait of internal salty oceans (Cochrane et al 2021;Weiss et al 2021). Thus, a Uranus orbiter would dramatically improve our understanding of the surface and interior of Ariel, as well as the other Uranian moons, thereby helping us determine whether these moons are, or were, ocean worlds Cartwright et al 2021;Leonard et al 2021;Bierson & Nimmo 2022;Cohen et al 2022).…”

Section: Future Workmentioning

confidence: 99%

Ariel's Elastic Thicknesses and Heat Fluxes

Beddingfield¹,

Cartwright²,

Leonard³

et al. 2022

Planet. Sci. J.

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The surface of Ariel displays regions that were resurfaced in the geologically recent past. Some of these regions include large chasmata that exhibit evidence for flexure. To estimate Ariel's heat fluxes, we analyzed flexure associated with the Pixie Group of chasmata, including Pixie, Kewpie, Brownie, Kra, Sylph, and an unnamed chasma, and the Kachina Group of chasmata, which includes Kachina Chasmata. We analyzed topography of these chasmata using digital elevation models developed for this work. Our results indicate that Ariel's elastic thicknesses range between 4.4 ± 0.7 km and 11.4 ± 1.4 km across the imaged surface. The younger Kachina Group has a relatively low elastic thickness of 4.4 ± 0.7 km compared to most chasmata in the older Pixie Group (4.1 ± 0.3 km to 11.4 ± 1.4 km). A pure H2O ice lithosphere would correspond to heat fluxes ranging from 17 to 46 mW m−2 for the Kachina Group and from 6 to 40 mW m−2 for the Pixie Group. Alternatively, if NH3 hydrates are present in Ariel's lithosphere, then the estimated heat fluxes are lower, ranging from 3 to 18 mW m−2 for the Kachina Group and from 1 to 16 mW m−2 for the Pixie Group. These results indicate that accounting for NH3 hydrates in the lithosphere substantially alters the resulting heat flux estimates, which could have important implications for understanding the lithospheric properties of other icy bodies where NH3-bearing species are expected to be present in their lithospheres. Our results are consistent with Ariel experiencing tidal heating generated from mean motion resonances with neighboring satellites in the past, in particular Titania and Miranda.

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Section: Future Workmentioning

confidence: 99%

Ariel's Elastic Thicknesses and Heat Fluxes

Beddingfield¹,

Cartwright²,

Leonard³

et al. 2022

Planet. Sci. J.

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“…They conclude that although ocean detection would be very difficult at Oberon, detection at Titania may be still be possible with the proper flyby characteristics (e.g., flyby altitude of 200 km was sufficient for detection of a 40-50-km thick ocean). The study conducted by Weiss, Biersteker, Colicci, Goode, et al (2021) focuses on magnetic induction for all moons of Uranus, but also considers the implications of compositional and thermal evolution of the moons, thus conveniently providing bounds on the extensive set of moon interior models used in our work. We also note that the magnetic field assessment at each of the moons for both of these works is in good agreement with our results.…”

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confidence: 99%

In Search of Subsurface Oceans Within the Uranian Moons

et al. 2021

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The Galileo mission to Jupiter discovered magnetic signatures associated with hidden subsurface oceans at the moons Europa and Callisto using the phenomenon of magnetic induction. These induced magnetic fields originate from electrically conductive layers within the moons and are driven by Jupiter's strong time‐varying magnetic field. The ice giants and their moons are also ideal laboratories for magnetic induction studies. Both Uranus and Neptune have a strongly tilted magnetic axis with respect to their spin axis, creating a dynamic and strongly variable magnetic field environment at the orbits of their major moons. Although Voyager 2 visited the ice giants in the 1980s, it did not pass close enough to any of the moons to detect magnetic induction signatures. However, Voyager 2 revealed that some of these moons exhibit surface features that hint at recent geologically activity, possibly associated with subsurface oceans. Future missions to the ice giants may therefore be capable of discovering subsurface oceans, thereby adding to the family of known “ocean worlds” in our Solar System. Here, we assess magnetic induction as a technique for investigating subsurface oceans within the major moons of Uranus. Furthermore, we establish the ability to distinguish induction responses created by different interior characteristics that tie into the induction response: ocean thickness, conductivity and depth, and ionospheric conductance. The results reported here demonstrate the possibility of single‐pass ocean detection and constrained characterization within the moons of Miranda, Ariel, and Umbriel, and provide guidance for magnetometer selection and trajectory design for future missions to Uranus.

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“…Images of the satellite surfaces can be used to obtain surface compositions indicative of subsurface ocean-surface interaction (infrared) and topographic information to investigate tectonics and geodynamics associated with a subsurface ocean, as well as map and analyze geologic units and surface features (visible). Observations of an induced magnetic field associated with any of the moons would also be indicative of a subsurface ocean (e.g., Arridge & Eggington 2021;Weiss et al 2021).…”

Section: Satellite Sciencementioning

confidence: 99%

The Case for a New Frontiers–Class Uranus Orbiter: System Science at an Underexplored and Unique World with a Mid-scale Mission

et al. 2022

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Current knowledge of the Uranian system is limited to observations from the flyby of Voyager 2 and limited remote observations. However, Uranus remains a highly compelling scientific target due to the unique properties of many aspects of the planet itself and its system. Future exploration of Uranus must focus on cross-disciplinary science that spans the range of research areas from the planet’s interior, atmosphere, and magnetosphere to the its rings and satellites, as well as the interactions between them. Detailed study of Uranus by an orbiter is crucial not only for valuable insights into the formation and evolution of our solar system but also for providing ground truths for the understanding of exoplanets. As such, exploration of Uranus will not only enhance our understanding of the ice giant planets themselves but also extend to planetary dynamics throughout our solar system and beyond. The timeliness of exploring Uranus is great, as the community hopes to return in time to image unseen portions of the satellites and magnetospheric configurations. This urgency motivates evaluation of what science can be achieved with a lower-cost, potentially faster-turnaround mission, such as a New Frontiers–class orbiter mission. This paper outlines the scientific case for and the technological and design considerations that must be addressed by future studies to enable a New Frontiers–class Uranus orbiter with balanced cross-disciplinary science objectives. In particular, studies that trade scientific scope and instrumentation and operational capabilities against simpler and cheaper options must be fundamental to the mission formulation.

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Searching for Subsurface Oceans on the Moons of Uranus Using Magnetic Induction

Cited by 28 publications

References 49 publications

Ariel's Elastic Thicknesses and Heat Fluxes

Ariel's Elastic Thicknesses and Heat Fluxes

In Search of Subsurface Oceans Within the Uranian Moons

The Case for a New Frontiers–Class Uranus Orbiter: System Science at an Underexplored and Unique World with a Mid-scale Mission

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