Pluto's Antipodal Terrains Imply a Thick Subsurface Ocean and Hydrated Core

Denton, C. A.; Johnson, Brandon C.; Wakita, Shigeru; Freed, A. M.; Melosh, H. J.; Stern, S. A.

doi:10.1029/2020gl091596

Cited by 11 publications

(16 citation statements)

References 49 publications

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“…Assuming further an impactor of density 920 kg ⋅ m −3 (Johnson et al., 2016) and basin diameter 1,000 km (Nimmo, Hamilton, et al., 2016), Equation gives impactor diameter of ∼400 km, which is in agreement with, for example, Denton et al. (2020). Values of all parameters are given in Table 2.…”

Section: Numerical Modelsupporting

confidence: 81%

“…Recent simulations by Denton et al. (2020) who model the formation of Sputnik Planitia by an impact and track the resulting stress waves through Pluto also support the hypothesis.…”

Section: Introductionmentioning

confidence: 78%

“…On the other hand, immediately after the impact, the clathrate layer might have been much thinner than our model assumes. Recent impact simulations by Denton et al (2020) show that the ice shell might have been locally disrupted by enormous excavation of the impact region, which makes the preservation of a uniform layer doubtful. For the lack of better knowledge, we adopted the thickness values that are, according to Kamata et al (2019), the most favorable to slow down the uplift relaxation, that is, 5 and 10 km for 100 and 200 km thick ice shell, respectively.…”

Section: Discussionmentioning

confidence: 99%

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Evolution of Pluto's Impact‐Deformed Ice Shell Below Sputnik Planitia Basin

2022

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Sputnik Planitia basin, the dominant surface feature of the dwarf planet Pluto, is located very close to the far point of Pluto‐Charon tidal axis. This position is currently believed to be a result of whole body reorientation driven by the combination of (a) the uplift of a subsurface ocean in response to a basin‐forming impact and (b) the nitrogen layer accumulated inside the basin. Since an ice shell made of pure water ice cannot maintain the uplift on timescales of billions of years, the presence of an insulating and highly viscous layer of methane clathrates at the base of the shell has recently been proposed. In this study, we solve the thermo‐mechanical evolution of the ice shell in a 2D spherical axisymmetric geometry and evaluate the gravity anomaly associated with the evolving ice shell shape. Taking into account the effect of impact heating and stress‐dependent rheology of both ice and clathrates, we show that a thick shell (≥200 km) loses the impact heat slowly which leads to fast uplift relaxation of the order of hundreds of million years. On the contrary, a thin shell (∼100 km) cools down quickly (∼10 Myr), becoming rigid and more likely to preserve the ocean/shell interface uplift till the present. These results suggest that a thick ocean may be present beneath Pluto's ice shell.

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Section: Numerical Modelsupporting

confidence: 81%

“…Recent simulations by Denton et al. (2020) who model the formation of Sputnik Planitia by an impact and track the resulting stress waves through Pluto also support the hypothesis.…”

Section: Introductionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

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Evolution of Pluto's Impact‐Deformed Ice Shell Below Sputnik Planitia Basin

2022

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“…As another example, Johnson et al (2016) modeled the formation of the Sputnik Planum basin and found consistency with a 220 km diameter projectile; however, they assumed a 2 km s −1 speed typical for impacts on Pluto. There is a considerable amount of literature surrounding each of these craters, which raises a number of other interpretations than those listed here (e.g., Artemieva & Pierazzo 2009;Denton et al 2021) and echoes the difficulties of inferring projectile properties from their craters. We note that impacts in the solar system virtually never exceed 100 km s −1 ; hence, these speeds are seldom modeled in the literature.…”

Section: Introductionmentioning

confidence: 81%

Identifying Interstellar Object Impact Craters

Laughlin¹

2022

Planet. Sci. J.

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The discoveries of two interstellar objects (ISOs) in recent years have generated significant interest in constraining their physical properties and the mechanisms behind their formation. However, their ephemeral passages through our solar system permitted only incomplete characterization. We investigate avenues for identifying craters that may have been produced by ISOs impacting terrestrial solar system bodies, with particular attention toward the Moon. A distinctive feature of ISOs is their relatively high encounter velocity compared to asteroids and comets. Local stellar kinematics indicate that terrestrial solar system bodies should have experienced of order unity ISO impacts exceeding 100 km s−1. By running hydrodynamical simulations for projectiles of different masses and impact velocities up to 100 km s−1, we show how late-stage equivalence dictates that transient crater dimensions alone are insufficient for inferring the projectile’s velocity. On the other hand, the melt volume within craters of a fixed diameter may be a potential route for identifying ISO craters, as faster impacts produce more melt. This method requires that the melt volume scales with the energy of the projectile while the crater diameter scales with the point-source limit (subenergy). Given that there are probably only a few ISO craters in the solar system at best, and that transient crater dimensions are not a distinguishing feature for impact velocities, at least up to 100 km s−1, identification of an ISO crater proves a challenging task. Melt volume and high-pressure petrology may be diagnostic features once large volumes of material can be analyzed in situ.

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“…The evidence at Ceres (radius of 470 km) therefore suggests that larger worlds (radius >700 km), such as Uranus's moons Titania and Oberon, and trans-Neptunian objects such as Pluto, Eris, Haumea, and Makemake may also host subsurface liquid today. Indeed, there are hints that Pluto may harbor an ocean (Keane et al 2016;Nimmo et al 2016;Denton et al 2021). On the other hand, Pluto's moon Charon, with a radius of ≈600 km and heliocentric distance of ≈40 au, seems to have fully refrozen ).…”

Section: Long-term Persistence Of Liquid Water In the Absence Of Tida...mentioning

confidence: 99%

Science Drivers for the Future Exploration of Ceres: From Solar System Evolution to Ocean World Science

et al. 2022

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Dawn revealed that Ceres is a compelling target whose exploration pertains to many science themes. Ceres is a large ice- and organic-rich body, potentially representative of the population of objects that brought water and organics to the inner solar system, as well as a brine-rich body whose study can contribute to ocean world science. The Dawn observations have led to a renewed focus on planetary brine physics and chemistry based on the detection of many landforms built from brines or suspected to be emplaced via brine effusion. Ceres’ relative proximity to Earth and direct access to its surface of evaporites that evolved from a deep brine reservoir make this dwarf planet an appealing target for follow-up exploration. Future exploration, as described here, would address science questions pertinent to the evolution of ocean worlds and the origin of volatiles and organics in the inner solar system.

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Pluto's Antipodal Terrains Imply a Thick Subsurface Ocean and Hydrated Core

Cited by 11 publications

References 49 publications

Evolution of Pluto's Impact‐Deformed Ice Shell Below Sputnik Planitia Basin

Evolution of Pluto's Impact‐Deformed Ice Shell Below Sputnik Planitia Basin

Identifying Interstellar Object Impact Craters

Science Drivers for the Future Exploration of Ceres: From Solar System Evolution to Ocean World Science

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