Geological Society of America

T178 Friends of Hoth: Episode II—Icy Bodies of the Solar System (Posters)

Monday, 23 October 2017
9:00 AM - 6:30 PM
Halls 4EF

INFERRING THE COMPOSITION AND MECHANICAL PROPERTIES OF THE NEAR-SURFACE OF CERES FROM EMPLACEMENT MODELING OF LAYERED/PANCAKE-LIKE EJECTA DEPOSITS

Paper number: T178-4
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Kynan H.G. Hughson Presenting Author
Georgia Institute of Tecjnology, Atlanta, GA
Christopher T. Russell
University of California, Los Angeles, Los Angeles, CA
Britney E. Schmidt
Johns Hopkins University Applied Physics Laboratory, Laurel, MD
Heather Chilton
Georgia Institute of Technology, Atlanta, GA
Jennifer Scully
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
Hanna Sizemore
Planetary Science Institute, Tucson, AZ
Shane Byrne
University of Arizona, Tucson, AZ
Thomas Platz
Max Planck Institute for Solar System Research, Göttingen
Carol A. Raymond
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA

Abstract

During the Survey, High Altitude Mapping Orbit, and Low Altitude Mapping Orbit phases of the primary mission Dawn’s Framing Camera observed a multitude of globally distributed lobate deposits. These flows were broadly interpreted as either similar to ice-cored/ice-cemented flows (Type 1 flows) on Earth and Mars, long run-out terrestrial or martian landslides (Type 2 flows), or highly mobile fluidized ejecta-like deposits (Type 3 flows) (Buczckowski et al., 2016; Schmidt et al., 2017). The Type 3 flows are morphologically similar to layered/pancake ejecta found on Mars and Ganymede where they are thought to be caused by impacts into ground ice rich substrates (Mouginis-Mark, 1979; Boyce et al., 2010). The main structural difference between these putative cerean fluidized ejecta flows and their martian/ganymedean counterparts is that the latter tend to form full aprons around the entire circumference of their parent crater, while the former generally only occur around a fraction of the circumference (usually < 180º) of their parent crater.

We assess the effects of target material strength, sliding friction, and vapor entrainment on the production of these features by comparing the ejecta mobility (EM: the ratio of the radius of the ejecta blanket to the radius of the parent crater) values for all Type 3 cerean flows to a ballistic/kinematic sliding model similar to the one developed by Weiss et al. (2014) to model EM for impacts into a variety of ground ice rich substrates of differing volatile content on Mars. Initial results suggest that, in order for these features to form, the cerean surface requires a large coefficient of sliding friction (>0.1), and that significant amounts of water be vaporized during impact. However, the model does not tightly constrain the strength of the target material (best-fit values range from granite-like to unconsolidated-sand-like). These results are consistent with a largely dry, rough, and thin surface layer underlain by material rich in pore-filling ground ice, even at low latitudes. Future implementation of this model will further incorporate compositional and geophysical knowledge attained from Dawn in order to better constrain the strength of the cerean surface.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-304251

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