Ready for Their Close-up: Insights about Occator's Bright Faculae Derived from New, Highest Resolution Observations of Ceres
Abstract
One of the most intriguing features Dawn observed on Ceres are the bright regions (faculae) in Occator crater. Occator (92 km diameter) contains a central bright region (Cerealia Facula), bright regions in the eastern floor (Vinalia Faculae), extensive lobate materials and a central dome within a central pit. Analyses based on Dawn data obtained from orbits of ≧385 km altitude led to the conclusion that Occator and the faculae's formation were either entirely driven by impact-induced processes, or that an endogenic component may also have contributed to their formation (synthesized in Scully et al., 2018). Subsequently, Dawn observed Ceres from its lowest altitude orbits of ≧35 km. Here we evaluate the ≧385 km altitude-based results/hypotheses and find that many are corroborated by the ≧35 km altitude data. However, in some cases, more analysis appears to be necessary. For example, initial analysis of the ≧35 km altitude data appear to indicate that the Vinalia Faculae predate prominent fractures, from which they were hypothesized to originate on the basis of the ≧385 km altitude data. To unravel relationships such as this we create a detailed geologic map of Occator's interior using the ≧35 km altitude Framing Camera data, from which we derive a relative stratigraphy. The detailed geologic map and relative stratigraphy allow us to test whether all features in Occator are likely the result of the evolution/solidification of an impact slurry, or whether endogenically-driven cryovolcanism also occurred. For example, we test whether the central dome, perched bright materials, channel-like features and isolated mounds could all form as brines/other volatile rich materials were squeezed to the surface as the impact slurry froze. Using the map and stratigraphy we also investigate topics such as: (a) whether the prominent fractures associated with the Vinalia Faculae were reactivated, (b) the origin of mounds in the lobate materials, (c) the origin of the dark material, (d) the distribution and size of small bright/dark depressions, to infer their formation mechanism and the subsurface distribution of bright/dark materials, and (e) the strength of materials. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Government sponsorship acknowledged.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.P24A..03S
- Keywords:
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- 6024 Interiors;
- PLANETARY SCIENCES: COMETS AND SMALL BODIESDE: 6055 Surfaces;
- PLANETARY SCIENCES: COMETS AND SMALL BODIESDE: 6063 Volcanism;
- PLANETARY SCIENCES: COMETS AND SMALL BODIESDE: 6205 Asteroids;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS