Post-impact cryo-hydrologic formation of small mounds and hills in Ceres’s Occator crater

Schmidt, B. E.; Sizemore, H. G.; Hughson, K.; Duarte, K. D.; Romero, V.; Scully, J. E. C.; Schenk, P.; Buczkowski, D. L.; Williams, D. A.; Nathues, A.; Udell, K.; Castillo‐Rogez, Julie; Raymond, C. A.; Russell, C. T.

doi:10.1038/s41561-020-0581-6

Cited by 16 publications

(20 citation statements)

References 31 publications

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“…The detection of H 2 by Cassini's Ion and Neutral Mass Spectrometer (INMS) was confirmed and interpreted as a signature of hydrothermal activity 3 . These discoveries pointed to ocean worlds like Enceladus, but also Europa in the Jovian system and recently Ceres in the asteroid belt 4,5 , as possibly harboring conditions that resemble Earth's habitable hydrothermal vents [6][7][8] (Fig. 1a).…”

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confidence: 96%

Bayesian analysis of Enceladus’s plume data to assess methanogenesis

et al. 2021

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Observations from NASA's Cassini spacecraft established that Saturn's moon Enceladus has an internal liquid ocean. Analysis of a plume of ocean material ejected into space suggests alkaline hydrothermal vents on Enceladus' seafloor. On Earth, such deep-sea vents harbor microbial ecosystems rich in methanogenic archaea. Here, we use a Bayesian statistical approach to quantify the probability that methanogenesis (biotic methane production) might explain the escape rates of molecular hydrogen and methane in Enceladus' plume, as measured by Cassini instruments. We find that the observed escape rates (i) cannot be explained solely by the abiotic alteration of the rocky core by serpentinization; (ii) are compatible with the hypothesis of habitable conditions for methanogens; (iii) score the highest likelihood under the hypothesis of methanogenesis, assumed the probability of life emerging is high enough. If the probability of life emerging on Enceladus is low, the Cassini measurements are consistent with habitable yet uninhabited hydrothermal vents and point to unknown sources of methane (e.g., primordial methane) awaiting to be discovered by future missions.

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Section: Main Textmentioning

confidence: 96%

Bayesian analysis of Enceladus’s plume data to assess methanogenesis

et al. 2021

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“…3). Occator's domes and mounds may originate from eruptive and/or frost-heave-like processes derived from the solidification and expansion of the lobate material 20,27 . Examination of terrestrial impact-derived hydrothermal deposits shows that hydrothermal deposits mainly occur in crater-fill materials, the inside and outer margin of central uplifts, the ejecta, the crater rim and in crater-lake sediments 28 .…”

Section: Resultsmentioning

confidence: 99%

“…1 and 2). The subtle basal scarp is possibly suggestive of an intrusive origin for Cerealia Tholus, such as formation via frost-heave-like processes 27 , or formation as a laccolith/from volume expansion of a volatile reservoir 19 . Alternatively, if Cerealia Tholus formed extrusively, the subtle basal scarp could be attributed to the material having a sufficiently low viscosity to form a gradually sloping surface instead of a clear termination scarp, or venting of ice and gas could result in the erasure of a clear termination scarp 31 .…”

Section: Resultsmentioning

confidence: 99%

“…Vinalia Faculae are located in the hummocky lobate material, which is proposed to form via inflation resulting from the injection of an ice/salt intrusion 36 . We investigate the possibility that the faculae-forming brine effusion resulted from the solidification and expansion of the water-ice-rich lobate material, similar to the formation mechanism proposed for the domes and mounds 27 . Water-ice-rich lobate flows, such as those in Occator (~200-600 m thick), would cool and solidify in the range of a few 1000-100,000s years.…”

Section: Methodsmentioning

confidence: 96%

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The varied sources of faculae-forming brines in Ceres’ Occator crater emplaced via hydrothermal brine effusion

et al. 2020

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Before acquiring highest-resolution data of Ceres, questions remained about the emplacement mechanism and source of Occator crater's bright faculae. Here we report that brine effusion emplaced the faculae in a brine-limited, impact-induced hydrothermal system. Impact-derived fracturing enabled brines to reach the surface. The central faculae, Cerealia and Pasola Facula, postdate the central pit, and were primarily sourced from an impactinduced melt chamber, with some contribution from a deeper, pre-existing brine reservoir. Vinalia Faculae, in the crater floor, were sourced from the laterally extensive deep reservoir only. Vinalia Faculae are comparatively thinner and display greater ballistic emplacement than the central faculae because the deep reservoir brines took a longer path to the surface and contained more gas than the shallower impact-induced melt chamber brines. Impactderived fractures providing conduits, and mixing of impact-induced melt with deeper endogenic brines, could also allow oceanic material to reach the surfaces of other large icy bodies.

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“…6 and 9-14) are consistent with continued release of volatiles from beneath the crater floor and LFD after emplacement. Crystallization of the impact melt slurry at Occator likely involved sediments coming out of suspension and salts and ice coming out of solution, creating secondary fluids and gases that may have extruded onto LFD surfaces 15,16,36 to form some of the local pitting and perhaps some of the sinuous troughs and brighter knobs. Cooling and crystallization of impact-heated materials below the crater floor may also have driven volatiles to the surface 10,14-16 .…”

Section: Resultsmentioning

confidence: 99%

Impact heat driven volatile redistribution at Occator crater on Ceres as a comparative planetary process

et al. 2020

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Hydrothermal processes in impact environments on water-rich bodies such as Mars and Earth are relevant to the origins of life. Dawn mapping of dwarf planet (1) Ceres has identified similar deposits within Occator crater. Here we show using Dawn high-resolution stereo imaging and topography that Ceres' unique composition has resulted in widespread mantling by solidified water-and salt-rich mud-like impact melts with scattered endogenic pits, troughs, and bright mounds indicative of outgassing of volatiles and periglacial-style activity during solidification. These features are distinct from and less extensive than on Mars, indicating that Occator melts may be less gas-rich or volatiles partially inhibited from reaching the surface. Bright salts at Vinalia Faculae form thin surficial precipitates sourced from hydrothermal brine effusion at many individual sites, coalescing in several larger centers, but their ages are statistically indistinguishable from floor materials, allowing for but not requiring migration of brines from deep crustal source(s).

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Post-impact cryo-hydrologic formation of small mounds and hills in Ceres’s Occator crater

Cited by 16 publications

References 31 publications

Bayesian analysis of Enceladus’s plume data to assess methanogenesis

Bayesian analysis of Enceladus’s plume data to assess methanogenesis

The varied sources of faculae-forming brines in Ceres’ Occator crater emplaced via hydrothermal brine effusion

Impact heat driven volatile redistribution at Occator crater on Ceres as a comparative planetary process

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